Answer:
140
Explanation:
I think you mean "lowest common denominator" where you use the word "benchmark."
The LCD of 3/7 and 16/20 is 140; 140 is the smallest number evenly divisible by both 7 and 20.
Then 3/7 → 60/140 and 16/20 → 112/140. 112/140 is between 1/2 and 1.