Question

12 boys and 16 girls can do a piece of work in 10 days while 13 boys and 24 girls can do the same work in 8 days. Find the time taken by 15 boys and 20 girls to do the same work

Answer 1

Answer:

12 and 1/2 days or 12.5 days

Step-by-step explanation:

let boys be a and girls be b

12a + 16b = 10-----------eq.1

13a + 24b= 8-------------eq.2

Then,

15a + 20b = ?

Solving eq.1 and eq.2 we get a and b

eq.1 *(3/2) = 18a + 24b = 15

eq.2 =. 13a + 24b = 8

subtract : 5a = 7

a=(7/5) and b = -(17/40)

So,

15(7/5) + 20(-17/40) = ( 840-340)/40 = 500/40 = 12.5