Answer:
2Al2O3 --> 4Al + 3O2
Step-by-step explanation:
Ok so balancing equations means that there is an equal amount of atoms on both sides.
So let's list how much there is on each side
Reactants:
Al-2
O-3
Products:
Al-1
O-2
First of all, oxygen has 2 on the products side but 3 on the reactants side. If you add a 2 to Al2O3 and a 3 to O2, they will have the same amount.
Al-4
O-6
-----
Al-1
O-6
Ok now we need the Al to be balanced. This can be done by putting a 4 in front of Al.
Al-4
O-6
-----
Al-4
O-6
It looks like a lot of work but over time you should be able to just look at it and know what's missing!!