Summary of the Math: Percent Change
Read and Discuss
- A percent can describe a change in a value—for example, a percent increase.
- If a value increases by x%, you can calculate the new value in two ways:
- Calculate x% of the original amount and add the result to the original amount.
- Calculate (100% + x%) of the original amount.
- For example, if the percent increase is 5% and the original amount is m, then:
0.05 + m = the total amount, or 1.05m = the total amount
- These two equations are equivalent because:
0.05m + m = 1.05m
0.05m + 1m = 1.05m(0.05 + 1)m = 1.05m
- For a problem about a sales tax situation, create a table that can help you organize what is given and what you need to find?
- Use a table to make a graph?
- Determine one of the amounts in a sales tax situation—the price of an item, the amount of the sales tax, or the total cost—if you know the other two amounts?