Maths question Solve the following system:?

x − 2y = 6
−7.5x + 15y = −45

You have two lines. Where they cross, both equations are solved by the same values, so it is called a simultaneous system. It looks like this: www.wolframalpha.com/input/?i=plot+x+%E2%88%92+2y+%3D+6,+%E2%88%927.5x+%2B+15y+%3D+%E2%88%9245

Right away we notice that the two lines are identical.
x − 2y = 6
-2y = -x + 6
y = x/2 - 3 Slope intercept form, slope = 1/2

−7.5x + 15y = −45
15y = 7.5x - 45
y = x/2 - 3 Same line!