NO3^-1 + Sn^+2 ---> NO + Sn^+4
Do you know how to balance redox equations? If you do I can help by pointing out to you the elements that have changed oxidation state. N changes from +5 on the left to +2 on the right. Sn changes from +2 on the left to +4 on the right. Can you take it from there? If not, please explain exactly what you don't understand about it.