The answer is 10 because the number 500 is basically 100%, so we can write it down as 500=100%. X is 2% of the output value, so we can write it down as x=2%. we have two equations now:500=100% and x=2%so we can do 500/x=100%/2% The Solution for what is 2% of 500. now we have:
2% of 500=10