One rate of an equivalent ratio is 9/n. select two other rates, one that can be solved using equivalent fractions, and the other that can be solved with unit rates

The values given is not sufficient.
However, the rates could 18/2n or 90/10n

In essence, rate is comparison between ratios.  While ratio is comparison between two or more numbers. Further, ratio on one hand, involves numbers either in amount, size, measurement, degrees, percentages or fractions with the absence of specific unit of measurement. On the contrary, rate is comparing quantities, amounts or unit of events happened expressed in a specific measurement or expressed under time. Take for instance, an example, Joe eats 2 while John eats 4 meals in a day. The ratio can be Joe: John, 2:4 meals. While the rate, is Joe eats 2 meals/day and John 4 meals/day.