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A variable needs to be eliminated to solve the system of equations below. Choose the correct first step.

{:[-8x+7y=30],[4x-7y=-22]:}
Add to eliminate 
x.
Subtract to eliminate 
y.
Add to eliminate 
y.
Subtract to eliminate 
x.

A variable needs to be eliminated to solve the system of equations below. Choose the correct first step.\newline8x+7yamp;=304x7yamp;=22 \begin{aligned} -8 x+7 y & =30 \\ 4 x-7 y & =-22 \end{aligned} \newlineAdd to eliminate x \mathbf{x} .\newlineSubtract to eliminate y \mathbf{y} .\newlineAdd to eliminate y \mathbf{y} .\newlineSubtract to eliminate x \mathbf{x} .

Full solution

Q. A variable needs to be eliminated to solve the system of equations below. Choose the correct first step.\newline8x+7y=304x7y=22 \begin{aligned} -8 x+7 y & =30 \\ 4 x-7 y & =-22 \end{aligned} \newlineAdd to eliminate x \mathbf{x} .\newlineSubtract to eliminate y \mathbf{y} .\newlineAdd to eliminate y \mathbf{y} .\newlineSubtract to eliminate x \mathbf{x} .
  1. Identify Opposite Coefficients: We have the system of equations:\newline8x+7y=30-8x + 7y = 30\newline4x7y=224x - 7y = -22\newlineTo eliminate a variable, we look for coefficients that are opposites or can be made into opposites. Here, we notice that the coefficients of yy are 77 and 7-7, which are already opposites.
  2. Add Equations to Eliminate yy: Since the coefficients of yy are opposites, we can add the two equations together to eliminate yy. The addition will result in the yy terms canceling each other out.\newline(8x+7y)+(4x7y)=30+(22)(-8x + 7y) + (4x - 7y) = 30 + (-22)
  3. Perform Addition and Simplify: Performing the addition, we get:\newline8x+4x+7y7y=3022-8x + 4x + 7y - 7y = 30 - 22\newline4x=8-4x = 8\newlineThis shows that adding the two equations eliminates yy.