To balance this equation first write down the nine by or atoms on both sides of the equation
Left side Right side
N = 2. N = 1
H = 2. H = 3
Next balance the N atoms first by placing 2 on the right side. Now.
Left side Right side
N = 2 N = 2
H = 2. H = 6
Finally place the coefficient of 3, on the left side for hydrogen and you have a balanced equation:
Left side Right side
N = 2 N = 2
H = 6. H = 6.
N2 + 3H2 => 2NH3.