At a game of billiards, A can give B 15 points in 60 and A can give C to 20 points in 60. How many points can B give C in a game of 90?
Answer: C
A : B = 60 : 45.
A : C = 60 : 40.
B/C = B/A x A/C = 45/60 x 60/40 = 45/40 = 90/80 = 90 : 80.
B can give C 10 points in a game of 90.