What is the ratio of the rise to the run if the rise is 3/2 and run is 5

I'm not sure of what you are asking, but the ratio of rise to run (whatever they might be) is given by:

rise : run

and you replace rise by its value, and run by its value, and then simplify.

Say the length of the tail of a mouse is 10 cm and the length of the mouse is 20 cm. The ratio if its tail to its whole body is 10 : 20 = 1 : 2