The correct answer is 1.
Step-by-step explanation:
The way this is written, everything after the words "divided by" would be calculated first; it is written as though this is a grouping, such as 20/(2*(5+5)). We would evaluate the innermost parentheses first; 5+5=10. Then this gives us 2*10=20 in our parentheses. 20/20 = 1.