John assembles computers and sells prebuilt computers as a business. The parts for the computer cost $800.  He sells the computers for 1.4 times the value of the components.  He manages to build 60 computers a month.  He has to pay $5000 a month in rent and another $3000 in non-rent extra expenses a month.  How much profit does he make a month?
He sells each computer for 1.4*800=$<T>multiply(1.4, 800)=1120.0
That means he makes a profit of 1120-800=$<T>subtract(1120, 800)=320 per computer
So he makes 320*60=$<T>multiply(320, 60)=19200 from selling computers
He has extra expenses of 5000+3000=$<T>add(5000, 3000)=8000 a month
So his profit is 19200-8000=$<T>subtract(19200, 8000)=11200
