Mr. robinson has 20 students on his martial arts class. the ratio of boys to girls is 4:1. how many boys and giris are in mr. Robinson's class?

16 boys and 4 girls

Since there is 20 students ... and the ratio is 4:1

To get to 16:4 you multiply 4 to get 16 and multiply 1 by 4 to get 4.

Now that it is 16:4 there is a total of 20 students ...

Since the ratio of boys to girls is 4:1, we can represent the number of boys as 4x and the number of girls as 1x.

We know that the number of boys + girls = 20. (total number of students)

4x + 1x = 20

5x = 20

Divide by 5 ...

x = 4

Now that we know x = 4 ...

Number of boys = 4x = 4 (4) = 16

Number of girls = 1x = 1 (4) = 4