I'm a little stumped on this question and not sure how to proceed.

It says simplify.
The problem is the fraction 5 3/4rs divided by the fraction 4 1/2st
So, 5 3/4rs/ 4 1/2st
I know you have to multiply by the reciprocal, but how do you do it when letters are involved? (and those letters, rs and st are with the fractions)

Thank you

Simplify this ratio

5 3/4 rs = 23rs/4

4 1/2 st = 9st/2
now divide and you get
23rs/4 * 2/9st = 46rs / 36st = 23r / 18t