Qd= 12 – P Qs = 1/3*P

Im trying to find the equilibrium price and quantity. but unsure how to do this with the fraction, silly i know!

I know it is 12-P=1/3*P

but can someone break down the steps as to how you arrive at P because ive been told the answer is 9. I get stuck when manipulating the fraction

(SORRY. IVE SOLVED IT. SILLY ME)