You solve this by plugging one equation into the other. Usually you have to rewrite one equation to make this work. In this case I choose to rewrite y-4x=0 as y=4x. After plugging it into the second, you get: 3x + 6*4x = 9 => 27x = 9 => x=1/3 Putting this solution back into y=4x gives us y=4/3
What is the solution of y − 4x = 0 and 3x + 6y = 9?