Let the total number of people surveyed by y.
we can solve this by using algebra.
to find the percentage of a number in terms of decimals or integers, just multiply the total by the percentage,
so with this question,
y x 40% = 20
shift x40% to the other side and turn it into /40%
y = 20 / 40%
change the percentage into decimals for easier calculations,
y = 20 / 0.4
y = 50
therefore, the answer to this is 50 people.