The substitution method:

Solve for x in the second equation and substitute it into the first equation. The result is
✔ 2(–3 + 2y) + 5y = –6.

The elimination method:

To eliminate x,
✔ multiply the second equation by –2
and then add the equations.

If the coefficient of y in the first equation was
–4 instead of 5, then the system would have
✔ infinitely many solutions.