Chapter 1 - Foundations for Algebra - 1-1 Variables and Expressions - Practice and Problem-Solving Exercises - Page 7: 14

2h + 13

We are asked for a sum, so we know that we must add the two things listed. The first thing listed is "twice a number h." Because it is twice the number h, we know that we must multiply h by two, giving us 2h. We add this to the second thing listed, 13, to obtain: 2h + 13.