write an equation to find the number of students in mr. boggs homeroom if the total number of stdents is 90

The number of students in Mr. Boggs's homeroom is equal to b. Add the total number of students in each class and set it equal to 90.

90 = b + 1.5 (b + 2) + 15 + (2b - 9)

Use the Distributive Property, and collect like terms. 90 = b + 1.5b + 3 + 15 + 2b - 9

90 = 4.5b + 9