Answer
6Li + N2 -> 2(Li3N)
Work Step by Step
Li + N2 -> Li3N
First we balance Li. We have 3 on the right and 1 on the left so we multiply the left Li by 3 to give
3Li + N2 -> Li3N
Next we have 2 Ns on the left and only 1 on the right so we multiply the right by 2 to give
3Li + N2 -> 2(Li3N)
This gives us 6 Li now on the right so we multiply the left 3Li by 2
6Li + N2 -> 2(Li3N)