Matt needs to buy new plates for his home.  He only wants to do dishes once a week.  Three days a week it is only him and his son eating and they use 1 plate each.  On the remainder of the days, his parents join them and everyone uses 2 plates that day.  How many plates does he need to buy?
So for 3 of the days, there are 1+1=2 people eating
So for those days they use 3*2=<T>multiply(3, 2)=6 plates
On 7-3=4 days the parents join them
On those days there are 2+2=<T>add(2, 2)=4 people eating
They use 4*2=<T>multiply(4, 2)=8 plates
So they use 8*4=<T>multiply(8, 4)=32 plates
That means they use a total of 32+6=<T>add(32, 6)=38 plates
