can a ratio be negative?

Answer 1

Sure.

For example, your car loses (negative) del V = - 5 m/sec speed for every del t = 10 seconds it travels. What is the rate of slowing per second? Let a = del V/del t (the ratio); so that a = del V/del t = -5 m/sec//10 sec = - 5 m/sec^2.

And there you have it, a negative ratio that, in this example, is commonly called deceleration.

Answer 2

yes a ratio is just a fraction. in some cases the sign might be irrelevant though.

Answer 3

yes it can. aratio is just a fraction and fractions can be negative.