Li invests money in a savings account. she wants to know the amount of simple interest that she will earn in 6 years at 3.75 percent. what additional information does she need to find this amount?

the given 6 = w/p is equivalent to 6p = w, where w is the total area of the walls and p is the area covered by a single can of paint.

knowing that 6 cans of paint will be needed, 6p = w becomes 6(6) = w = 36.   this tells us that the total area to be painted is 36 square units.