*This Math quiz is called 'Algebra - Percentage Operations (Advancing)' and it has been written by teachers to help you if you are studying the subject at middle school. Playing educational quizzes is a fabulous way to learn if you are in the 6th, 7th or 8th grade - aged 11 to 14.*

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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, using the following formula will help you to find the solution to your problem.

The % increase or decrease = the difference between the known factors divided by the base factor. Now letâ€™s work this out in a practice problem below.