Answer :

PEMDAS

so do the stuff in the parenthesis first
5+5=10
so  we get
20/2(10)
then multiply or divide left to right
20/2=10
10*10 = 100

therefore your answer would be 100


do parentheses first (5+5) = 10

Then do 20/2 divide it equals 10

The numbers outside the parentheses means to multiply so 10x10 =100