Question

The sum of three numbers is 69. If the second number is equal to the first diminished by 8, and the third number is 5 times the first. What are the numbers?

If x represents the first number, then which of the following equations could be used to solve the problem?


x = 6x - 8
69 = 6x - 8
69 = 7x - 8

Answer 1

We let x as the first number
y the second number
z is the third number

x + y + z = 69
y = x -8
z = 5x

We substitute the equations,
x + x-8 + 5x = 69
7x - 8 = 69 The answer for the second question.

x = 11
y = 3
z = 55

Answer 2

x = first number
x - 8 = 2nd number
5x = 3rd number

x + x - 8 + 5x = 69
7x - 8 = 69 <=== this is the equation u would use

7x - 8 = 69
7x = 69 + 8
7x = 77
x = 11

1st number = 11
2nd number : x - 8 = 11 - 8 = 3
3rd number : 5x = 5(11) = 55