A group of girls were dancing. Four boys joined in, and then there were eight people dancing in total. How many girls were there?
The question tells us a group of girls were dancing. We’re not sure how many there were, and then four boys joined in, and then there were eight people dancing in total. We need to find the number of girls. We can use the inverse operation to help us find the missing number.
An inverse operation is an operation which is opposite. Subtraction is the opposite of addition. If we start with the total number of dancers and subtract the number of boys, that would tell us the missing number or how many girls were dancing. Eight take away four is four. There were four girls.