Question

A farmer divides his herd of n cows among his four sons so that one son gets one - half the herd, the second, one-fourth , the third son, one-fitth and the fouth, 7 cows , then n is

• A. 180
• B. 140
• C. 240
• D. 100

Answer 1

The correct option is B 140

$\frac{n}{2}+\frac{n}{4}+\frac{n}{5}+7=n$
or $n-\frac{n}{2}-\frac{n}{4}-\frac{n}{5}=7$
or $\frac{20n-10n-5n-4n}{20}=\frac{7}{1}$
or $\frac{n}{20}=\frac{7}{1}$
or n=20$\times$7=140