Simultaneous Equations

Could someone please tell me how to work this simultaneous equation out, it is revision for a university exam.

y=3x+9
y=2x+7

Please show your workings.

Thanks.

Both equations equal y, so set them equal to each other to solve for x.

3x + 9 = 2x + 7 (subtract 9 from both sides)
3x = 2x - 2 (subtract 2x from both sides)
x = -2

Now go back to one of the equations (it doesn't matter which) to solve for y.

y = 3x + 9
y = 3(-2) + 9
y = -6 + 9
y = 3

ANSWER: (-2, 3)

Subtract equation 2 from equation 1, you will have "y-y=3x-2x+9-(+7)" that will be 0=x+9-7(recall that -1*1=-1). Then 0=x+2(subtract 2 from both sides), you'll have x=-2. Likewise to solve for y, put 'x' into any of the eqns i.e y=3x+9, y=3(-2)+9, y=-6+9, y=3. X=-2 & y=3 CHECK{Y=3X+9, Y-3X=9, put y=3& x=-2 u'll have '3-3(-2)=9,3+6=9, 9=9.

y=3x+9
y=2x+7

y=3x+9x2
y=2x+7x3

y=6x+9
y=6x+7

-

y=2