One way of applying the elimination method:
Multiply equation (2) by -5:
Now add equation (1) and equation (3) to eliminate :
Now substitute the value of into any equation and solve for .
This is what is taught in schools (so don't shoot me ....)
You add so that x gets eliminated.
I have (reasonably) assumed that you have some familiarity with the method ....
Read this: Systems of Linear Equations: Solving by Addition / Elimination