1) j(x)=-2/3x

what is j(x)'s y-intercept?
answer: (0,0)

2) k(x)=4
what is k(x)'s slope?
answer: 0

3) g(x)=2x-5
what are the root(s) of g(x)?

4) the slope of line p if p is perpendicular to line f

are the answers i provided correct? and please help me on 3 and 4

the roots are where g(x) = 0.

So, you want

2x-5 = 0
x = 5/2

two lines are perpendicular if their slopes are negative reciprocals. That is, if line P has slope p, and line F has slope f, p*f = -1

Your first two answers are correct.