Needing some help with this question on my homework and cant get this right

Each unit of a product can be made on either machine A or machine B. The nature of the machines makes their cost functions differ. 2 Machine A: C(x) = 20 + X_ e 3 Machine B: C(y) = 220 + Y_ 9 Total cost is given by C(x,y) = C(x) + C(y). How many units should be made on each machine in order to minimize total costs ifx + y =10,100 units are required? The minimum total cost is achieved when E units are produced on machineAand D units are produced on machine B. (Simplify your answer.)