13- zy+4y so all you have to do is plug the numbers in like this:
(5)(2)+4(2) then simplify so (2)(5) is 10 then (4)(5) is 20 so all there left to do is add so your final answer for question 13 is 30.
15- p^2/4-m so again plug the numbers in like this 4^2/4-3 then simplify so 4 to the second power is 16 so now it look like this 16/4-3 and then again simplify so 16 divide that by 4 to get 4 so now your problem is way small XD so 4-3 is 1 so your final answer for question 15 is 1.
~Good Luck~
