7 carpet-weavers can weave 7 carpets in 7 days. At the same rate, how many carpets would be woven by 14 carpet-weavers in 14 days? Pick.
A) 14  B) 28  C) 21  D) 35  E) none of these

Rationale: explanation : solution : let the required number of carpets be x . more weavers , more carpets ( direct proportion ) more days , more carpets ( direct proportion ) weavers 7 : 14 } : : 7 : x days 7 : 14 . ' . 7 * 7 * x = 14 * 14 * 7 < = > x = 14 * 14 * 7 / 7 * 7 = 28 . answer : b
Answer: B