Respuesta :
For a percentage question setup is like this:
part = percentage * whole
part = 72
percentage = 80% = 0.8
72 = 0.8 * whole
whole = 72/0.8 = 90
part = percentage * whole
part = 72
percentage = 80% = 0.8
72 = 0.8 * whole
whole = 72/0.8 = 90