Math Wiki
In order to understand the information on this page, it can be helpful to already know:


Evaluation by substitution is to take an algebraic expression and substitute (replace) each variable with its value.

For example, if x=3 and y=5 then the following expression can be evaluated by replacing the variable names with the corresponding number each time they occur:

Worked Examples

{coming soon}


You can practice skills in percent using the following references:

Khan Academy

Make sure you are logged in to Khan Academy when doing these exercises so your practice is recorded.


Percentages are often used in financial applications where a proportion calculation is required. These include:

  • Discounts (percentage of original price)
  • Profit margin (percentage of sale price)
  • Tips (percentage of total bill)
  • Loan or Deposit interest (percentage of balance)

Next Steps

Comfortable with percents? Check out the follow-on mathematics you can now do: