36 is 80% of what number

If 36 is 80% ( a piece) of a number. that means the number must be higher than 36

Changing the English to math:

36 = 80% x n  (n being the number)
36= .8n  (changed the percent to a decimal by moving it back two places
36 = .8n
.8      .8    I divided both sides by .8 - when you divide a number by a decimal (less than one) the number will become larger.
The answer is 45