Question

Help. Explain how you would use the substitution method to solve the following system of equations.

5x - y = -2
10x - 3y = -7

Answer 1

Start with the top equation. Express it in terms of y.

\[5x-y=-2\]
\[-y=-5x-2\]
\[y=5x+2\]

Answer 2

Now we can substitute the solved value of y of the top equation to the bottom equation.

10x-3y=-7
10x-3(5x+2)=-7

Answer 3

Then solve the equation for x.

10x-3(5x+2)=-7
10x-15x-6=-7
-5x-6=-7
-5x=-1
x=1/5

You can solve for y by substituting x = 1/5 to any of the original equations.

For more information: http://chilimath.com/algebra/intermediate/subs/substitution-method.html