Just solve x + 3y = 7 for x!
x + 3y + −3y = 7 + −3y > We have to add -3y to both sides.
x = −3y + 7
We need to substitute −3y + 7 for x in 2x + 6y = 9
2x + 6y = 9
2(−3y+7) + 6y = 9
14 = 9 > Now simplify both sides
14 + −14 = 9+ −14 > Add -14 to both sides now!
0 = −5
So yes it is true that this has no solutions!