Is this relation a function? Yes, this is a function.
No, this is not a function, just a relation.

Barbara deposited $300 in the bank. if the bank pays her simple interest at the rate of 4 percent per year, how much money will she have in her account at the end of 9 months?

Two corresponding sides of two similar triangles are 3cm and 5cm. the area of the first triangle is 12cm^2. what is the area of the second triangle?

Is it greater than or less than7*3_9*2