10 ounces is in 4 pizzas so if we want 15 pizzas we need to count up
4 can not fit into 15 so we have to stop at 12 pizzas.
Now we need to add 3 pizzas
:Note: that one pizza is 2.5 of an ounce out of 10 ounces
so after you add the 3 pizzas you have 15 but that wasnt 4 pizzas so you have 2.5 ounces left over you add those ounces to the 30 you got from the 12 ounces which you have 30 and add it to the ounces left over
