the ratio of boys to girls is 7:1. if there are 66 more boys than girls, work out how many girls there are

Answer 1

b = boys

g = girls

Turn the two statements into equations:

b = 7 * g <== the number of boys is 7 times that of girls (boys to girls 7:1)

b = g + 66 <== There are 66 more boys than girls

Now set the two equations equal about the b:

7g = g + 66 | -g

6g = 66 | /6

g = 11

Now replace the g with 11 in one of the original equations:

b = 7 * g

b = 7(11)

b = 77

There are 11 girls and 77 boys.