What is the equation look like when the line is perpendicular to y= 4-3x and has y intercept of 3/4?

Eewww. "What is the equation look like"?

The given line has slope -3
So, your new line needs slope 1/3

If the equation is written as
y = mx+b, then the y-intercept of (0,3/4) means that

3/4 = 1/3 (0) + b
b = 3/4

and the line is

y = 1/3 x + 3/4