Evaluate expressions with unknown variables (advanced)

The  exercise appears under the Algebra I Math Mission. This exercise practices substituting into expressions for several variables simultaneously.

Types of Problems
There is one type of problem in this exercise:


 * 1) Evaluate the expression: This problem provides an equation (possibly two) with several variables and an expression involving those variables. The student is asked to find the value of the expression and write it in the space provided.Ewuv1.png

Strategies
An ability to visualize the expression and how it looks when distributed would assist with completing this exercise accurately and efficiently.
 * 1) On this exercise the coefficients on the equations are the different. This makes it more complicated to find the final answer because the values of the coefficients become more important.
 * 2) The value of the instance of the variables in the expression is the coefficient in the expression divided by the coefficient in the equation times the numerical value of the equation.
 * 3) On paper, the step-by-step process would be to factor a GCF out of the expression where appropriate, then substitute the value of the equation for it.

Real-life Applications

 * 1) Strategies like the ones needed for this exercise are common on standardizes tests and some math competitions such as AMC and AIME.