Is this usage of 'it' wrong according to GMAT?

[AZ679]

On page 107, Manhattan SC book, 5th Edition:

"She will pay you clearly after you take out the garbage and have proven it!"

However, there is no reasonable antecedent for pronoun 'it'.

1. Is this usage wrong according to GMAT?
2. How can we solve this issue?
Is '... and have proven doing so' , for example, fine?
Any other better suggestions?

[RonPurewal]

1. Is this usage wrong according to GMAT?

it's wrong. you can't use "it" to stand for an action/a verb.

more importantly, there's no such thing as "according to GMAT".
this is VERY important to understand. the gmat tests only things that are universal in the formal written english language, all around the globe.
• nothing that is contested/controversial is tested.
• nothing that differs from one country to another is tested.
• there are no arbitrary conventions chosen by GMAC; there is absolutely nothing, ever, that is uniquely "gmat english".

[RonPurewal]

2. How can we solve this issue?
Is '... and have proven doing so' , for example, fine?
Any other better suggestions?

you don't have to write SC sentences, so this type of question is a waste of your time (in terms of gmat preparation, at least).