a) We can plug in $358 into A(w), since A(w) represents the amount of money Dale needs. So,
358 = 700 - 18w
Subtract: -342 = -18w
Divide: w = 19 weeks
b) We can plug in 6 into w, since w represents the number of weeks Dale saves money. So,
A(w) = 700 - 18(6)
Multiply: A(w) = 700 - 108
Subtract: A(w) = $592
