Hello from MrBillDoesMath!
Answer: infinite solutions
Discussion: I did a double take on this one but the left hand is
a + 3 + 2a = 3a +3
and the right hand side is
-1 + 3a + 4 = 3a + (4-1) = 3a + 3
The left and right sides of the equation are identical for all "a", i.e. for infinitely many "a" values.
Regards, MrB.