Let x,y and z be the three numbers.
The sum of the numbers is 69. Therefore
x + y + z = 69 (1)
The second number is equal to the first diminished by 8. Therefore
y = x - 8 (2)
The third number is 5 times the first. herefore
z = 5x (3)
Substitute (2) and (3) into (1).
x + (x - 8) + 5x = 69
x + x - 8 + 5x = 69
7x - 8 = 69
7x = 69 + 8 = 77
x = 77/7 = 11
From (2), y = x-8 = 11-8 = 3
From (3), z = 5x = 5*11 = 55
Answer: The numbers are 11, 3, and 55
We showed that 7x - 8 = 69, or that 69 = 7x - 8
