Working Together on a Science Project

Jessica and Mark are working together on a science project. They have a total of 120 pages of research material to review. Jessica can review the material at a rate of 5 pages per hour, while Mark can review at a rate of 8 pages per hour.

If they work together for a total of $t$ hours, how many pages will they have reviewed after this time?

Express the total number of pages reviewed as a function of $t$.