Question 77967
x(x/5)/x+(x/5)=20
(x^2/5)/[(5x+x)/5]=20 
(x^2/5)/(6x/5)=20 cross multiply
(x^2/5)=20(6x/5)
x^2/5=120x/5
x^2-120x=0
x(x-120)=0
x=0
x-120=0
x=120 hours answer. amount of time it takes for Jay alone.
120/5=24 hours for Carman alone. 
proof
120*24/(120+24)=20
2880/144=20
20=20