There are some boys and cows at a place. If total number of heads is 15 and total number of legs is 46, then how many boys and how many cows are there?

Options

A. 8 boys and 7 cows
B. 9 boys and 6 cows
C. 7 boys and 8 cows
D. 6 boys and 9 cows

Answer

C

Explanation

Let the number of cows are A and the number of boys are B. Then -
4A+2B = 46
and A+B=15
` therefore A=15 -B`
` therefore 4(15-B)+2B=46`
` implies 60-4B+2B =46`
`implies 2B =14`
`therefore B=7`
and A=8