No because he will be $3.00 short. So it is $0.75 a bottle. So then you multiply $0.75 by 20. You get $15.00 So David will not have enough in his wallet.
Area of a regular pentagon = pa/2, where p = the perimeter and a = the apothem. If you don't know the perimeter, calculate it from the side length: p = 5s, where s is the side length.