Question

how to balance an equation

Answer 1

balancing an equation is easy
you have to just care about haw much of mole of you have of the reactants and the product for example let me generalize this thing for you
you have the eq
we have
$P_{4} + O_{2}$===>$P_{4}O_{10}$
so
we have 4moles of (P) on LHS
and 2moles of O also
but we have 10 moles of O in RHS
so you multiply LHS, O with 5 to make it balance
and you are left with
$P_{4} + 5O_{2}$===>$P_{4}O_{10}$

Answer 2

We just have to balance both side of equation....... :)
Eg- H2 + O2 = H2O + energy
Balancing......... :)
2H2 + O2 = 2H2O + energy