Compound X contains elements A and B at an approximate ratio, by weight, of 2:10. Approximately how many grams of element B are there in 324 grams of compound X?
Choices:
A) 54  B) 162  C) 250  D) 270  E) 322

Rationale: "total number of fractions = 2 + 10 = 12 element b constitutes = 10 out of 12 parts of x so in 324 gms of x have 324 * 10 / 12 = 270 gms of b and 324 - 270 = 54 gms of a . cross check : - a / b = 54 / 270 = 2 / 10 ( as given ) ans d"
Answer: D