In a game of 60, A can give B 10 points, and in a game of 75, B can give C 15 points. How many points can A give C in a game of 90?

Explanation

1. 01

   A : B = 60 : 50 = 6 : 5 and B : C = 75 : 60 = 5 : 4, so A : C = 6 : 4 = 3 : 2.

2. 02

   When A scores 90, C scores $\frac{2}{3} \times 90 = 60$: A can give C 30 points.