Question

A school set up a new sports club. In the first week, 8 girls and 7 boys went to the club. In the second week, another 2 girls and some more boys joined the club. The number of boys in the club was now double the number of girls. How many boys joined the club in the second week?

Answer 1

1st week: g = 8; b = 7
2nd week: g = 8 + 2; b = 2g
If there are 10 girls by the second week, and the number of boys doubles that number, then there are 20 boys.

2nd week: b = 20

Now if 20 boys are present in the second week, that means that 13 boys joined in the second week as:

Boys Joining in 2nd Week = 20 - 7 (boys that went in the first week)

So 13 boys joined the club in the second week.