By the end of the 8th grade Eva had performed in 36 dance recitals. That was equal to 82% of all the recitals that she attended. How many recitals did Eva attend by end of the 8th grade?

Some algebraic problems will ask you to find an unknown percentage increase or an unknown percentage decrease between two known factors. An unknown factor is a variable.  

When asked to find a percentage increase or decrease, use the following formula:
The % increase or decrease = the difference between the known factors divided by the base factor.  Now let’s work this out in a practice problem below.