Walking with 4/5 of my usual speed, I miss the bus by 4 minutes. What is my usual time?  Choose the correct option: 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 : 5 1 - - - - - - - - 4 4 - - - - - - - - - ? è 16 answer : a"
Answer: A