Question

What will the first step look like in a substitution problem?

y=2x
x+y=9​

Answer 1

x + 2x = 9

General Formulas and Concepts:

Algebra I

• Solving systems of equations using substitution/elimination

Explanation:

Since we are using substitution, we must replace one variable in 1 equation as the 2nd equation.

We are given:

y = 2x

x + y = 9

Here we see that y equals 2x. We can go ahead and replace in the 2nd equation y.

x + 2x = 9

And we would solve from there.