Walking with 4/5 of my usual speed, I miss the bus by 3 minutes. What is my usual time? Select.
A) 16 min  B) 26 min  C) 34 min  D) 20 min  E) 12 min

Rationale: speed ratio = 1 : 4 / 5 = 5 : 4 time ratio = 4 : 51 - - - - - - - - 3 4 - - - - - - - - - ? è 12 answer : e
Answer: E