Question

I need help with number 4.... please explain because I don't understand

Answer 1

y=mx+d

you know m=1/3
->
y=(1/3)x+b

for the complete definition of the line you need to calculate b, for this insert the given point (3,3) into x and y which the line passes:

3=(1/3)*3+b
3=1+b
2=b

so your line is y=(1/3)x+2