Hi there!
Let's solve this inequality step by step!

First divide both sides by 2.

To find the value of a, we must get rid of the negative sign in front of it, so we divide both sides by -1. When dividing by a negative, we must flip the sign.
Hence,

Additonal note:
This solution makes sense because of the following reason: when a number that has been made negative is bigger than 3, the number itself must be smaller than -3 (when we add an extra minus sign to -3, it becomes 3; so every number smaller than -3 will become bigger than 3 when we add another minus sign).
~ Hope this helps you!