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?
30 points
20 points
10 points
12 points
Explanation:
A : B = 60 : 45.
A : C = 60 : 40.
$\therefore \dfrac{B}{C} $=$ \left(\dfrac{B}{A} \times\dfrac{A}{C} \right) $=$ \left(\dfrac{45}{60} \times\dfrac{60}{40} \right) $=$ \dfrac{45}{40} $=$ \dfrac{90}{80} $= 90 : 80.
$\therefore$ B can give C 10 points in a game of 90.