Garfield decides to paint his 15 ft x 21 ft recreation room. His house has 9 ft ceilings. If a gallon of paint covers 400 sq ft, how many gallons of paint will be needed if he wants to put two coats of paint on the walls?

Rena used the steps below to evaluate the expression , when . step 1: substitute into the expression. step 2: simplify the parentheses. step 3: evaluate the power to a power. step 4: use reciprocals and find the value. in which step did rena make the first error?