Suppose you are given the system of equations
{ y=x-4, 6x+5y=12
a. Which variable would you replace in the substitution process?
b. What expression would replace that variable?
a. In the substitution process, the variable that is usually replaced is the one that is isolated or easily solved for in one of the equations. In this case, the variable "y" is isolated in the first equation, so we will replace "y" in the second equation.
b. The expression that replaces "y" is "(x-4)" since the first equation states that y = x-4. Therefore, in the second equation, we can substitute "y" with "(x-4)" to get 6x + 5(x-4) = 12.