Question

I have to balance the following equation using the lowest number of coefficients
CH4 + NH3 + O2 -- HCN + H2O

I can get N,C and O to balance as follows
CH4 + NH3 + O2 -- HCN + 2H2O

I can get H,C and N to balance as follows
CH4 + NH3 + 2O2 -- HCN + 3H2O

I just can't seem to get all four balanced. Can anyone tell me where I'm going wrong please?

2CH4 + 2NH3 + 3O2 -- 2HCN + 6H2O

This is an advanced problem, not for beginners. When you take on the concept of oxidation-reduction, it will become somewhat easier, but not easy.

Thankyou very much