The work is not much, I can manage it alone.

活儿不多，我一个人也忙得过来。

《新英汉大辞典》

That's not a hard job. I'm sure I can manage it myself.

这活儿又不重我一个人顶得下来。

《新英汉大辞典》

B: Thank you for offering, but I can manage it myself.

谢谢你，但我自己能行。

youdao

Good behaviour, if they can manage it, will probably earn them some more aid and perhaps investment.

ECONOMIST: North Korea

These days, setting up a cloud-based enterprise IT program is so easy that even non-IT types can manage it.

FORBES: Rethinking the Cloud

The western tourism industry will need to adapt quickly and intelligently to the demands of Chinese visitors but the prize is huge for those who can manage it.

ECONOMIST: Chinese tourism