To solve with the substitution method a system of two linear equations with two unknowns we will have to substitute one of the unknowns in some equation and thus obtain an equation with only one unknown.

**How do we do it?**

- Choose the equation in which you can easily isolate one of the unknowns (isolate it in such a way that it cannot express itself).
- Put the unknown that you have isolated in the second equation of the system: you will have an equation with one unknown and you will discover the value of the first one.
- Go back to the system of equations and place the value of the unknown you found in one of the equations or in the equation obtained to find the second unknown.