Reviewed by Rachelle Bencio Yu
15% of What Number is 12?
Answer: 15% of 80 is 12
This problem asks us to find the original number when 15% of it equals 12. Such questions are classic percentage problems in elementary algebra and are useful for solving real-life situations involving proportions, such as discounts, interest, or population statistics.
Methods
Math Tutor Explanation Using Setting Up an Equation Method
To find the unknown number, represent the question as an algebraic equation and solve for the variable.
Step 1: Step 1: Let the unknown number be x
Step 2: Step 2: Write the equation: 15% of x = 12, or 0.15 * x = 12
Math Tutor Explanation Using Reasoning with Proportions
You can also set up a proportion to relate the part, whole, and percentage.
Step 1: Step 1: Write the proportion: 15/100 = 12/x
Step 2: Step 2: Cross-multiply to get 15x = 1200
Step 1:
Step 2:
Math Tutor suggests: More Practice with Percentage and 'Of What Number' Problems
Expand your understanding of percentages and how to find the original number given a part. Try these similar exercises to sharpen your skills.
FAQ on Percentage Problems
How do I convert a percent to a decimal?
Divide the percent by 100. For example, 15% becomes 0.15.
What is the formula for finding the whole when a percent and part are given?
Use: Whole = Part / (Percent as decimal).
Can this method be used for any percentage problem?
Yes, set up the equation or proportion using the given values.
Why do we cross-multiply in proportions?
Cross-multiplying helps solve for an unknown when two ratios are equal.
What if the percentage is greater than 100%?
The process is the same, but the result may be larger than the part.
Math & reading from 1st to 9th grade
Looking for homework support for your child?
Choose kid's grade
