The sum of the digits of a certain two-digit number is 7. Reversing its digits increase the number by 9. What is the number?

Answers

Answer 1

Answer: Let the two numbers be x and y.

According to your question;

x + y = 7
10y + x = 10x + y + 9

By equation 1 ; x = 7-y

Substituting the value of x ;

10y + ( 7 -y) = 10(7-y) + y + 9

9y + 7 = 70 -10y + y + 9

9y + 7 = 70 - 9y + 9

=> 18y = 70 -7 + 9
=> 18y = 72
=> y = 4

Substituting for x ;

x = 7 - y
=> x = 7 -4
=> x = 3

Thus, x = 3 and y = 4;
=> The number is 34.

Answer 2

Answer: The original number is 34 .
The sum of its digits is (3 + 4) = 7 .
Reversing its digits makes it 43 . . . 9 more than 34.

How I did it: (There must be a much more elegant mathematical method)

There are only 6 possibilities for the original number.
They are . . .

16
25
34
43
52
61 .

Instead of trying to dream up a sophisticated equation,
I decided it was faster and easier to just go down the list
and look for one that worked.
The third one I tried worked.

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Can anyone do question 25 part c? :)

Answers

$\begin{cases}x^3\qquad\qquad\ \ \ when\ x\geq3\n5\qquad\qquad\quad \ when\ 0\ \textless \ x\ \textless \ 3\nx^2-x+2\quad\ when\ x\leq0 \end{cases}\n\n\n (a)\n f(0)\iff x=0\implies f(x)=x^2-x+2\n\nf(0)=0^2-0+2=2\n\n(b)\n \{f(2)\iff x=2;\ \ f(1)\iff x=1\}\implies f(x)=5\n\n f(2)=5\quad\wedge\quad f(1)=5\n\n f(2)-f(1)=5-5=0$

$(c)\n \big\forall \limits_( n\in R)\ n^2\geq 0\ \ \Rightarrow\ \ \big\forall \limits_( n\in R)\ (-n^2)\leq 0 \ \ \Rightarrow\ \ x\leq0\ \ \Rightarrow\ \ f(x)=x^2-x+2\n\nf(-n^2)=(-n^2)^2-(-n^2)+2=n^4+n^2+2$

0.63 cents plus what gives you 1.00

Answers

Answer:37 lol

Step-by-step explanation:

Answer:0.37

Step-by-step explanation: you subtract 0.63 by 1.00 to get 0.37

Select the property of equality used to arrive at the conclusion. If 5x = 20, then x = 4. the division property of equality the addition property of equality the subtraction property of equality

Answers

Answer: The division property of equality

Step-by-step explanation:

The division property of equality says that if we divide both sides of an equation by the same number then both the sides are still remains equal.

The given statement : - If 5x = 20, then x = 4.

By using the division property of equality the division operation is applied on both the sides of the equation such that both sides are divide by 5 to arrive the given conclusion .

Hence, the property of equality used to arrive at the conclusion = The division property of equality

the division property of equality because you divide 20 by 5 to get the x value.

put me as brainliest answer

Leo is running in a 5-kilometer race along a straight path. if he is at the midpoint of the path, how many kilometers does he have left to run?

Answers

Let us assume Leo starts from a point (0,0)

Since the total length of the race is 5 km, he will be at (5,0) at the end of the race.

It is given that, he is at the mid point of the race.

Mid point formula is : $((x_(1) +x_(2) ))/(2) , ((y_(1) +y_(2) ))/(2)$

Present coordinate : $(5+0)/(2) , (0+0)/(2) = (2.5,0)$

He still needs to run 5-2.5 = 2.5 km

What is the relationship between ratios 10/24 and 5/12, proportional or non-proportional? A. Proportional B. Non-proportional

Answers

Answer: Proportional

Reason: The fractions 5/12 and 10/24 are equal.

To go from 5/12 to 10/24, double both top and bottom

5*2 = 10

12*2 = 24

To go in reverse, divide both parts by 2

10/2 = 5

24/2 = 12

Two crews are laying blacktop on a road. They start at the same time at opposite ends of a 18-mile road and work toward one another. One crew lays blacktop at an average rate of 0.4 mile a day faster than the other crew. If the two crews meet after 5 days, find the rate of each crew.

Answers

total road length is 36 miles.
If one crew’s rate is x miles/day, the other is 1.4x miles/day.
The collective distance per day is x+1.4x,
so in five days the distance is 5(x+1.4x).
Set that equal to the total distance:
5(x+1.4x)=36
simplify:
x+1.4x=7.2
x(1+1.4)=7.2
x(2.4)=7.2
x=3

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