they give you the formula. Now let's plug numbers in.
it is A= 1/2 (15+12)8
remember PEMDAS, so parentheses first..
A= 1/2 (27)8
A=1/2(216)
if the 1/2 confuses you, just remember that that fraction is saying one half, and another way to represent halves are 0.5
so
A=108
hope this helps!