A farmer divides his herd of x cows among his 4 sons so that one son gets one half of the herd, the second gets one-fourth, the third gets one-fifth and the fourth gets 7 cows. Then x is equal to	Choose the correct choice from the following answers
A) 100
B) 140
C) 180
D) 160
E) 120

Rationale: no . of cows : : x 1 st son : x / 2 2 nd son : x / 4 3 rd son : x / 5 4 th son : 7 ( x ) + ( x / 4 ) + ( x / 5 ) + 7 = x = > x - ( 19 x / 20 ) = 7 = > ( 20 x - 19 x ) / 20 = 7 = > x = 140 answer : b
Answer: B