Yesterday, Chau had m baseball cards. Today, he gave 5 away. Using m, write an expression for the number of cards Chau has left.

If m = baseball cards he had yesterday, and today he got rid of 5, the expression is equal to

m - 5 = x.

As an example of what the answer is, replace m with 10.

If he had 10 baseball cards and gave away 5 today, x = 5.

The answer is m - 5 = x.