Algebra math problem i cannot get

Question

One number is 7 less than 3 times the second number. Their sum is 29. Find the numbers.

Let x be the second number. Write an equation and slove

Answer 1

If we use x to represent the second number, then we can write the following expression to represent the first number: 3x -7

So the first number is 3x - 7 and the second is x

We also know that their sum is 29, so can write the following equation to represent the sum:

3x - 7 + x =29

Solve this equation by combining like terms and using inverse operations:

3x - 7 + x = 29

4x - 7 = 29

4x - 7 + 7 = 29 + 7

4x = 36

4x/4 = 36/4

x = 9

So the second number is 9. The first one will be 3x - 7 and using x as 9 , the first number will be:

3x - 7 = 3*9 -7 = 27 - 7 =20

The first number is 20