We would be happy to get you started!
First;
You know that there is a y=mx+b form, therefore all you have to do is just get those equations in that form in order to get your slope and y-intercepts!
Take the first one for example: 3x+4y=8 All you have to do is this,
1. Subtract 3x from BOTH sides! = 4y=8-3x
2. Divide by 4 to get Y by itself to BOTH SIDES! = y=2-3/4x
3. Use the y=mx+b form to get your answers!
Therefore, your y-intercept is the one without the x so it is 2 and the slope is equal to -3/4! Hope this helps!