Representing and solving word problems involves choosing the correct operations (like addition or subtraction), as well as knowing which values to use.

To find the total number of books, add the three values.

Add the columns from right to left. Remember to regroup when a column's sum is greater than 9.

To find how many pages Darlene has left to read, subtract 5 and 10 from 20.

First, subtract 5 from 20.

Now, subtract 10 from 15.