Order

(7*(-3+5)-2/(-8-(-6))+15       simplify everything in the parentheses within the parentheses, first.....

(7*(2) - 2/(-8 + 6) )  + 15 =

(7*(2) - 2/(-2) ) + 15  =        perform the multiplications/divisions from left to right before any additions/subtractions

14 - (-1)  + 15  =    simplify

14  + 1 + 15 =  

30