Question

Help with this pleas

Answer 1

For an equation of a line in slope intercept form y = mx+b, m is the slope and b is the y-intercept. 
In the equation y = (-3/4)x + 3, the value of b here is 3, so 3 is the y-intercept. So the line should go through (0,3).

Answer 2

Simple, you have

y=-3/4x+3

Your y-intercept is 3. So it's at (0,3)

Then the -3/4

it basically means go down three points and go over four points.

So after (0,3) it's (4,0) then (8,-3) and so on.

Going positive it's (-4,6) then (-8,9) 
And so on and so forth.