90kg of an alloy A is mixed with 140 kg of alloy B. If alloy A has lead and tin in the ratio 3:4 and alloy B has tin and copper in the ratio 2:5, then the amount of tin in the new alloy is? Choices:
A) 100.6 kg  B) 95.4 kg  C) 117.5 kg  D) 91.4 kg  E) 92 kg

Rationale: "quantity of tin in 90 kg of a = 90 * 4 / 7 = 51.4 kg quantity of tin in 140 kg of b = 140 * 2 / 7 = 40 kg quantity of tin in the new alloy = 51.4 + 40 = 91.4 kg answer is d"
Answer: D