Dear sir

I apologize I'm typing in English. I can't operate Korean typewriter now. Thank you for your consideration.

In the textbook p.126, we have equation balancing questions.

#3 and #4 related to charge balancing are tricky to me.

In #3,

3Ag2S + 4Al -> 6Ag + 2Al2S3

I've got here, but I can't go further.

In #4,

I have no clue about this one.

Please help me and thanks for your precious time in advance.