I do not understand why my approach to the following CAT question is incorrect:-
If Jim earns x dollars per hour, it will take him 4 hours to earn exactly enough money to purchase a particular jacket. If Tom earns y dollars per hour, it will take him exactly 5 hours to earn enough money to purchase the same jacket. How much does the jacket cost?
(1) Tom makes 20% less per hour than Jim does.
(2) x + y = $43.75
SOLN
Jacket Price = 4x = 5y
(1) x=0.8y =>4*0.8y = 5y. I then solved for y to determine 5y
(2) x = 43.75-y => 4(43.75-y) = 5y. Again I solved for y to determine the price of the jacket, 5y.
As such, I chose (d) for my answer. MGMAT's soln treated this as a rate question - not sure why- and the result was different from what I got. Can someone say why is my approach incorrect?