Walking at 4/5 of his usual speed a man is 10 mins too late. find his usual time.  Choose the correct answer
A) 81 mins	B) 64 mins	C) 52 mins	D) 40 mins	E) None
speed=s,time=t,   4/5s*(t+10)=st   t=40   ANSWER:40 mins
<result>D</result>
Walking at 4/5 of his usual speed a man is 10 mins too late. find his usual time.