Match each expression with its simplified form.
- a/(a^2-4)+2/(3a+6)
2.5/a+7
3.a/ab-3/b
4.6/ab+8/a
5.3a/4b^2-b/6a
3.a/ab-3/b
4.6/ab+8/a
5.3a/4b^2-b/6a