if you do something alone and your friend say "加油",you can reply thx..And if you do the thing with your partner and he or she say "加油" to you ,you can say "加油",too

if someone say it to you, u can answer thank you! or 加油 too! both are right

you can say "好的，我会的！" which means "ok, i will!"

either modest silence or rude 住口 = zhù-kǒu = shut up