To get the slope and y-intercept, the equation has to be changed to slope-intercept form, or y=mx+b.
To get this, you need to get y by itself in the equation given. For this, first subtract 3x from both sides to get -2y = -3x +12. Then divide both sides by -2y to get the y by itself, and the resulting equation is y= -3x +12 / -2. You can also divide each value by -2, to get -3x / -2, which is 3/2 x, and 12/-2, which is -6. This means the slope is 3/2 and the y-intercept is -6.
Hope this helps.