In a group of 80 children, there are three times as many boys as girls. how many are there?

In the given question, there are several vital information's provided and they can be used to determine the required answer. Firstly it is already given that there are a total of 80 students in the group. It is also given that the number of boys is 3 times that of the number of girls.Then:
Let us assume that the number of girls in the group = x
Then the number of boys in the group = 3x
Now we can put the above information's to gether to find the number of boys and girls.
x + 3x = 80
4x = 80
x 80/4
x = 20
Then we can say that there are 20 girls in the group.
The number of boys = 3x
                                  = 3 * 20
                                  = 60
Then there are 60 boys in the group.

b ... the number of boys
g ... the number of girls
80 children

three times as many boys as girls ... 3 * g = b

If you would like to know how many boys and girls are in a group of 80 children, you can calculate this using the following step:

b + g = 80
3 * g + g = 80
4 * g = 80    /4
g = 80/4
g = 20 girls

b = 3 * g = 3 * 20 = 60 boys

Result: There are 60 boys and 20 girls.