Harry can rake the leaves in the yard 8 hours faster than his little brother Jimmy can.
If they join to work together they can complete the job in 3 hours.
1/x + 1/(x - 8) = 1/3
3(x - 8) + 3x = x(x - 8)
x^2 - 14x + 24 = 0
(x - 12)(x - 2) = 0
Solutions:
x = 2
x = 12
Jimmy can complete the job on his own in 12 hours.
