Walking 7/6 of his usual rate, a boy reaches his school 4 min early. Find his usual time to reach the school? Choose the correct choice from the following choices
A) 26 min  B) 22 min  C) 21 min  D) 20 min  E) 28 min
28 min   28 m   Speed Ratio = 1:7/6 = 6:7   Time Ratio = 7:6   1 -------- 7   4 --------- ? 28 min
<result>E</result>
Walking 7/6 of his usual rate, a boy reaches his school 4 min early. Find his usual time to reach the school?