x = 1st number, y = 2nd number, z = 3rd number
x + y + z = 142
x = y - 8
z = 4y
y - 8 + y + 4y = 142
6y - 8 = 142
6y = 142 + 8
6y = 150
y = 150/6
y = 25 <=== the 2nd number
x = y - 8
x = 25 - 8
x = 17 <== the 1st number
z = 4y
z = 4(25)
z = 100 <=== 3rd number