A perpendicular line has an opposite reciprocal slope. This means that the new line will have a slope of -4/3x. Plug in x and y into the equation y=Mx +b where m is the slope (-4/3):
-3=(-3/4)(-3) + b
and isolate b:
b-3=(-3/4)(-3)
b=(-3/4)(-3) +3
b=9/4+3
b=21/4
The final equation is y= -4/3x + 21/4
The y intercept is (21/4).
