Balancing an acid-base chemical reaction I tried balancing this chemical equation 
$$\mathrm{Al(OH)_3  + H_2SO_4 \to Al_2(SO_4)_3 + H_2O}$$
with a system of equations, but the answer doesn't seem to map well. I get a negative coefficient which is prohibitive in this equations. How do I interpret the answer?

Why don't you just use the actual chemical equation as input? http://www.wolframalpha.com/input/?i=Al(OH)3%2BH2SO4%E2%86%92Al2(SO4)3%2BH2O
