The first question is 54

(1+3)=4, (2 + 4) = 10, (3 + 5) = 18

If you follow the pattern adding +1 to both number into parenthesis you get:

(1+3)=4, (2 + 4) = 10, (3 + 5) = 18, (4+6) = X, (5+7) = Y, (6+8) = Z
Then, the solution is to take the numbers of a parenthesis and add the solution of the last one.

(2+4)+4 = 10
(3+5)+10 = 18
(4+6)+18 = 28
(5+7)+28 = 40
(6+8)+40 = 54

But the second question... I dont understand.