The number of fish in a lake decreased by 25% between last year and this year. This year there are 45 fish in the lake. What was the population of last year

The population of last year was 60.

Step-by-step explanation:

From the information given, as you know that the number of fish in a lake decreased by 25% between last year and this year, the amount of fish this year represents 75% of last year's population as: 100%-25%=75%. With that, you can use a rule of three to find last year's population tha would represent 100% given that 75% is equal to 45 fish.

75%   →  45

100%  →   x

x=(100*45)/75= 60

According to this, the answer is that the population of last year was 60.

yes because there is exactly one y value for every x value

for function there can't be more than one value for every x value