Isabella has a summer job working for a biologist studying a type of flower. Isabella's job is to collect these flowers from a local park. The biologist pays Isabella $48 per flower and a weekly base salary of $140. Last week, Isabella earned $572 from the biologist. Write an equation for Isabella's earnings last week.

Use f for the number of flowers, and write your equation in the form pf + q = r, where p, q, and R are numbers.

Now use your equation to calculate the number of flowers Isabella collected last week.