Sara can weed a garden in 30 minutes. When her brother Hamdan helps her, they can weed the same garden in 20 minutes. How long would it take Hamdan to weed the garden if he worked by himself?

a. Write an expression for Hamdan's rate, using n for the number of hours he would take to
weed the garden by himself.

b. Write an equation to show the amount of work completed when they work together.

c. How long would it take Hamdan to weed the garden by himself?