Question

The sum of three numbers is 129. The third number is 9 less than the first. The second number is 3 times the third. What are the numbers?

Answer 1

33, 72, and 24

Explanation:

Let's the three numbers are x, y, and z.

x + y + z = 129

z = x − 9

y = 3z

Solve the system of equations. Using substitution:

y = 3(x − 9)

y = 3x −27

x + (3x − 27) + (x − 9) = 129

5x − 36 = 129

5x = 165

x = 33

y = 3x − 27

y = 72

z = x −9

z = 24