Percent of Change / Commission / Sales Tax

At the bottom of this page you will find a section for making practice problems along with the answers. Additionally worksheets and answer keys can also be generated and printed.

    These are all "percent of problems". Commission is a percent of the sales, sales tax is a percent on the amount of the purchase, percent increase and percent decrease are both percents of the original or starting amount.

      Commission / Earnings
    1. Commission (C) -- the amount of money a person is paid based on their sales.
    2. Commission percent (C%) -- the commission percent.
    3. Sales (S) -- the amount of sales the commission is paid on.
    4. Earnings is the sum of someone's regular pay (P) and their commission.

    5. C = C%•S    ----     Commission = Commission% • Sales
    6. E = P + C     ----     Earnings = Regular Pay + Commission

      Sales Tax / Total Cost
    1. Tax percent (T%) -- the tax percent or tax rate paid on a purchase.
    2. Tax (T) -- the amount of money payed in tax on a purchase.
    3. Purchase (P) -- the amount of money payed for a purchase.
    4. Total cost (TC) -- the sum of the purchase price and the sales tax.

    5. T = T% • P     ----     Tax = Tax% • Amount of Purchase.
    6. TC = P + T     ----     Total Cost = Price + Tax.

      Percent of Increase / Percent of Decrease
    1. Change percent (C%) -- the percent of the change.
    2. Chang amount (C) -- the amount of the change, up or down, positive or negative.
    3. Starting amount, initial amount, beginning amount (S) -- the amount at the beginning or start.
    4. Ending amount, final amount (E) -- the amount at the end or when the change is finished.

    5. C = E - S     ----     amount of change = ending amount - starting amount.
    6. C% = C ÷ S     ----     percent of change = change ÷ starting amount.
    7. C% = (E - S) ÷ S     ----     another formula for the percent of change.

Problem # 1