The number of children at the library was 3 times the uninvited of adults. The total number of people at the library was 48. How many children were at the library?

Step-by-step explanation:

In equation form,

children + adults = 48 people at the library.

If the number of children is 3 times the number of adults, then in equation form:

children = adults*3

Let's call children c and adults a. Subbing the second equation into the first gives us an equation with only one unknown instead of 2.

c + a = 48 after making the substitution is

3a + a = 48 and

4a = 48 so

a = 12

There were 12 adults. If the total number of people was 48, then

48 - 12 = number of children so

c = 36