Jo's collection contains US, Indian and British stamps. If the ratio of US to Indian stamps is 4 to 2 and the ratio of Indian to British stamps is 5 to 1, what is the ratio of US to British stamps?	Choose the correct option.
A) 5 : 1 B) 10 : 5 C) 15 : 2 D) 20 : 2 E) 25 : 2

Rationale: "u / i = 4 / 2 i / b = 5 / 1 since i is multiple of both 2 ( as per first ratio ) and 5 ( as per second ratio ) so let ' s assume that i = 10 i . e . multiplying teh first ratio by 5 and second ration by 2 in each numerator and denominator then , u : i : b = 20 : 10 : 2 i . e . u : b = 20 : 2 answer : option d"
Answer: D