The answer is p = 2.
Here are the steps I did.
1. Expand ( 3 - 2p = 4p - 9 )
2. Add 2p to both sides ( 3 = 4p - 9 + 2p )
3. Simplify 4p - 9 + 2p to 6p - 9 ( 3 = 6p - 9 )
4. Add 9 to both sides ( 3 + 9 = 6p )
5. Simplify 3 + 9 to 12 ( 12 = 6p )
6. Divide both sides by 6 ( 12/6 = p )
7. Simplify 12/6 to 2 ( 2 = p )
8. Now lastly switch it up ( p = 2 )