Asurvey found that 40% of shoppers at max a mart like chocolate ice cream is 20 shoppers likes chocolate ice cream how many people were surveyed

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.