Given that a and b are positive numbers, c and d are negative numbers, and a > b, c > d, then show that a/c < b/d
Wouldn't it be better to learn how to do it yourself? You learn mathematics by doing mathematics. Not by watching someone else do mathematics.
If c> d and c is negative, then 1< d/c. Do you see why? If d is also negative then 1/d> 1/c. That's what you need to do to prove this.