use rates, the rate a person is working is the reciprocal of the time
working together, they work at a rate of 1/3 job per hour
when two people work together their rates add together
---> 1/h + 1/j = 1/3
---> h = j - 8 (harry takes 8 hrs less than jimmy)
substitute and solve for j
1j−8+1j=13
combine fractions
j+(j−8)j(j−8)=13
cross-multiply
j2−8j=6j−24
j2−14j+24=0
Factor
(j−12)(j−2)=0
j = 12
It takes jimmy 12 hours to rake the leaves
