How old was mozart when he first composed a musical piece?

Two-door coupe, hoppin' out like jack-in-the-box, i'm gon' shoot if this 30's all that i got, y'all on mute, ain't no back-talk on my block, numb numb juice to the head, fok up the opps, two-door coupe, hoppin' out like jack-in-the-box, i'm gon' shoot if this 30's all that i got, y'all on mute, ain't no back-talk on my block, numb numb juice to the head, fok up the opps,