Respuesta :

Answer: 225

Step-by-step explanation:

kimberlyolivares474

Answer:

225

Step-by-step explanation:

so if the first day is 21 then the second day is 33 subtract that which is 12. 21 +12+12+12+12+12+12+12+12+12+12+12+12+12+12+12+12=225 the 18 day