Answer: Nonlinear.
Explanation:
A linear function can be graphed by a straight line and is constantly proportional with a degree of zero or one. To find if the given is linear or nonlinear, we will divide each y by its corresponding x and then compare.
Let us compute these values. I will use a calculator to be sure I don't make mistakes in the calculations.
(7) / (5 1/5) ≈ 1.34615
(5) / (2 4/5) ≈ 1.7857
(1) / (2/5) ≈ 2.5
These values are not all the same, so the given points are nonlinear.
We can also graph them and we see that they do not make a straight line. See attached.