Answer:
4x+10
Step-by-step explanation:
Emma is guaranteed to use 10 pages when she writes something. Since you can't tell how many hours she has written, you use x to represent the hours she has spent writing. If she writes 4 pages every hour, that would be 4 × (hours spent writing) or 4x. Add 4x to the original guaranteed 10 pages she uses and you have your expression.