If you solve a system and find $x=10$, what is the correct next step using back-substitution to find $y$?

Substitute $x=10$ into an original equation to find the value of $y$.

Substitute $y=10$ into an original equation to find the value of $x$.

Verify that $x=10$ works in both equations.

Write the solution as $(10, 0)$.

Solving Systems of Linear Equations by Substitution Practice — Grade 8 math