Burning of aluminium powder in excess oxygen produces white aluminium oxide powder. Balance chemical equation. Explain to me tq(*σ´∀`)σ​

4Al(s) + 3O2(g) —> 2Al2O3(s)

First, write out the unbalanced equation.
Al(s) + O2(g) —> Al2O3(s)

Balance the oxygens first. What do you need to multiply by to get to a common multiple of 2 and 3 to balance the oxygens? The common multiple is 6, so multiply the O2 by 3 and the Al2O3 by 2.

Al(s) + 3O2(g) —> 2Al2O3(s)

Now balance your aluminum. You have 1 in the reactants and 4 in the products, so multiply the reactant by 4.

4Al(s) + 3O2(g) —> 2Al2O3(s)

Hope this makes sense!