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?

33, 72, and 24

Step-by-step 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