Can somebody help me?

How do you determine whether a relationship represented as as graph is linear or nonlinear

What is the volume of a cone with a height of 6 cm in the radius of 2 cm

Campus rentals rents 2 and 3 bedrooms apartments for $700 ans $900 a month respectively. last month they had six vacant apartments and reported $4600 in lost rent. how many of each type of apartment were vacant?