algebra precalculus - In how many days can Sachin alone complete the work given the following conditions?

Alok and Sachin agree to complete a piece of work in $20$ days?They also agree to forfeit double the amount of wages corresponding to the uncompleted part of work,if they fail.If Alok alone can complete the work in $40$ days and they lost $1$/$3$ of the pay of the total work.In how many days can Sachin alone complete the work?

options:

a) $60$ b) $24$ c) $36$ d) $30$

MyApproach:

Alok+Sachin=$20$ Days

If they fail,They agree to forfeit double the amount of wages corresponding to the uncompleted part of work

If Alok alone can complete the work in $40$ days.

Therefore,Alok did 2.5% work in 1 day and given:(together)they did 5% work(20 days).

Therefore,Sachin do 2.5% work.

I am confused how to use these equations to solve the problem.

Can anyone guide me how to approach the problem correctly.