The students in science class spent 65% of the class period performing an experiment. how long is the class period if the time spent on this was 52 minutes

65% of an unknown time is 52 minutes.
Let the unknown time be x.

65% of x = 52

65% * x = 52

0.65x = 52

Divide both sides by 0.65

x = 80

The class period is 80 minutes.

52 or what they said ☝️