John decides to get a new apartment with a roommate.  His former rent was $2 per square foot for a 750 square foot apartment.  His new apartment cost $2800 per month, which he splits evenly with the roommate.  How much money does he save a year?
His old apartment cost 750*$2=$<T>multiply(750, 2)=1500 a month
His new apartment cost $2800/2=$<T>divide(2800, 2)=1400.0 a month
So he saves $1500-$1400=$<T>subtract(1500, 1400)=100 a month
That means he saves $100*12=$<T>multiply(100, 12)=1200 a year
