_h2o+_al2o3=__al(oh)3

3 H20 + 1 Al2O3 = 2 Al(OH)3

Explanation:

in this problem we are balancing the equation, that mean both side have to be same.

we are going to start with Al, notice the reactant side have 2 atoms of Al while the other side have one so we multiply by 2 now both side have 2 Al atoms

we move to O, in the product side we have 6 O atoms. 2 * 3 = 6 and reactant side have 3 + 1 = 4 but we can multiply the H20 by 3 and we will have the 6 O atoms in both reactant and product. if you notice now H atoms are balanced too. reactant side 3 * 2 = 6 and product 3* 2 = 6