Evaluate by Substitution

In order to understand the information on this page, it can be helpful to already know: Equivalent fractions Decimals Variable

Outline

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:

$2x-6y+y^2$

$=2\times 3 -6 \times 5 + 5^2$

$=6 - 30 + 25$

$=1$

Worked Examples

{coming soon}

Practice

You can practice skills in percent using the following references:

Khan Academy

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Application

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:

• Simple interest
• Compound interest
• Probability