Question

How do you solve `2x + 3y = 20` and `-4x - 6y = -28`?

Answer 1

This pair of equations has no solution; they represent a pair of parallel lines.

Explanation:

Notice that the left side of the second equation is exactly `(-2)` times the left side of the first equation, so th4e equations are either co-incident or parallel.
The right side of the second equation is not `(-2)` times the right side of the first equation; therefore the equations are parallel.