Question

Which sentences are correct?
1) Are you able to assist me on this matter? I would appreciate your assistance on this matter.
OR
2) Are you able to assist me in this matter? I would appreciate your assistance in this matter.

Thanks.

Answer 1

All are correct.

The first sentence in each pair asks a straight question. Under some circumstances it could be considered too direct.

The second sentences are more formal and more polite.

Answer 2

If a collegue is willing to assist, in a form of formal letter how do you respond?