hey im also quite late,
if a set of documents that would take beth 8 days would take mia 10 days,
one can deduce from this that each day beth does 1/8 of the documents and mia does 1/10 of the documents,
beth has already done 2 days worth of work,
so beth has done 2/8 or 1/4 worth of work,
therefore, 1-0.25=0.75 or 3/4 worth of work is left,
if beth and mia work together, they do 1/8 plus 1/10= 9/40 of the documents every day together,
therefore, 3/4- the amount of work left, divided by 9/40- the fraction of the documents they do every day while working together,
this brings the answer to be 10/3 or 3 and 1/3 days left or remaining,
thank you if this method helped everyone,
i have always likes mathematics