Simplify ratio of exponential functions

Question

I was struggling to see how to simplify this ratio of exponentials as below: $$\frac{\exp(-x_{i2}y - a_{i})}{\exp(-x_{i1}y - a_{i})} = \exp((x_{i1} - x_{i2})y)$$

Answer 1

Use the property that $\displaystyle \frac{e^a}{e^b}=e^{a-b}$.

Then, everything follows as such.