An archer needs to practice.  He intends to shoot 200 shots 4 days a week.  He is able to recover 20% of his arrows.  The arrows he uses cost $5.5 per arrow.  His team agrees to pay for 70% of the cost of his arrows.  How much does he spend for arrows a week?
He shoots 200*4=<T>multiply(200, 4)=800 shots per week
He can recover 800*.2=<T>multiply(800, 0.2)=160.0 of those arrows
So he uses 800-160=<T>subtract(800, 160)=640 arrows a week
The cost for those arrows would come out to 640*5.5=$<T>multiply(640, 5.5)=3520.0 per week
His team pays for 3520*.7=$<T>multiply(3520, 0.7)=2464.0 of that
So he has to pay 3520-2464=$<T>subtract(3520, 2464)=1056 per week for arrows
