I can give you a link https://youtu.be/aUy-_WnEV30 . I hope this answers your problem, and gives you greater insight. Sorry I couldn't do more :(
Substitute the values of a and b into the expression:
11 + 3 - 2
Add first because of order of operations (perform addition and subtraction in the order of occurrence from left to right):
14 - 2
Subtract (same justification as above just with subtraction instead):
12
Hope this helps!
Add one to the other side and y=1/2
B is your answer because if you check each one in the calculator B is the same as the expression and also 2^8 makes up the first part and the second half makes up the .24