There are three types of problems; all can be solved using this equation: Part = Percentage x Total
In that formula, the percentage is to be written as a decimal.
First type:
You want to know the percentage:
What percentage is 23 out of 86?
Percentage = Part / Total x 100 ---> Percentage = 23 / 86 x 100 = 26.7% (approximately)
You know the total amount and the percentage and you want to find the part:
How many are 35% of 219? (35% as a decimal is .35)
Part = Percentage x Total ---> Part = .35 x 219 = 76.65
You know the part and the percentage and you want to find the total:
75 is 42% of how many? (75% as a decimal is .75)
Total = Part / Percentage ---> Total = 75 / .42 = 178.6 (approximately)