Walking with 4/5 of my usual speed, I miss the bus by 7 minutes. What is my usual time?  Choose the most appropriate option:
A) 16 min B) 26 min C) 28 min D) 20 min E) 12 min
Speed Ratio = 1:4/5 = 5:4Time Ratio   = 4:51 -------- 7 4 --------- ? è 28   Answer: 28 min
<result>C</result>
Walking with 4/5 of my usual speed, I miss the bus by 7 minutes. What is my usual time?