Equalising Units Concept (Remainder)

Given: Before, One Side, Change Ratios, After Amount
Find: Change Amount

First
At first, the amount of money Abel had was 3/5 of the amount of money Simon had. They went for dinner together. Abel paid 1/4 of the bill and Simon paid for the rest. After paying for the dinner, Abel has $63 left and Simon has 1/4 of his money left. How much was the dinner?

(Before)
Abel : Simon
= 3 : 5
= 12 : 20

(Simon)
After : Change : Before
= 1 : 3 : 4
= 5 : 15 : 20

(Change)
Abel : Simon : Total
= 1 : 3 : 4
= 5 : 15 : 20

(After)
Abel = 12 u - 5 u = 7 u
7 u = $63

(Change)
Total = 20 u
20 u = $180