8 ounces* 20 days= 160 ounces
160 ounces divided by 16 ounces in a pound= 10 pounds
She will have fed tiny 10 pounds of dog food in 20 days.
It is 3.
You can check this by seeing 3^3 ie. 3x3x3, which comes out as 27.
You can check the cube root on a calculator.