Respuesta :
She will need 18 slices of cheese for 2 school days, because for one day she needs 9, 3 times 3, and for 2 days you would just double that.
So first you would multiply 3x2=6 then multiply 6x3=18 then that would be for one day so for 2 school days you would multiply 18x2=36 so,she would use 36 slices of cheese for 2 school days.