In Chase's art class, there are 21 students. Nine of them are girls. How many are boys?

Question

Please help me. I don't know what equation i do not get this

Answer 1

 

Let b = number of boys

Let g = number of girls

 

b + g = 21

 

b + 9 = 21

b = 21 -9

b = 12

 

There are 12 boys

Answer 2

Ok, the problem tells you there are 21 students and 9 of them are girls.  You want to find out how many boys there are, so let's show the boys as "b" ...

 

21 students - 9 girls = boys

 

21 - 9 = b

 

12 = b

 

So, now you know there are 12 boys.