it is a good way to earn money to....

[navi tasan]

Which are correct:

1-It is a good thing to be here.
2-It is a good thing, to be here.

3-It is a good thing being here.
4-It is a good thing, being here.

5-It is a good way to earn money to teach mathematics.
6-It is a good way to earn money, to teach mathematics.

7-It is a good way to earn money teaching mathematics.
8-It is a good way to earn money, teaching mathematics.


Sentences 5-8 are supposed to mean: 'Teaching mathematics is a good way to earn money.'


I don't think '5' and '7' really work.
'5' seems to be saying that something (the first 'it') is a good way to earn money in order to teach mathematics.
'7' seems to be saying that something (the first 'it') is a good way to earn money while teaching mathematics.

Gratefully,
Navi.

 

[bhaisahab]

5 to 8 don't work at all, in my opinion. I don't find any of them particularly natural.