Question

4a+6=2a+12

Answer 1

I take it that you are trying to solve for a from the given equation. When posting a question, always post the question explicitly to avoid unnecessary confusion.

4a+6=2a+12
Collect like terms (unknowns) on the left hand side, and constants on the righ:
4a-2a = 12 - 6
2a = 6
a=3