About four days. If you need to be exact:
Lets start by giving them the same denominator (multiply 1/5 by 6 and 5/6 by 5)
=6/30 and 25/30
now lets simplify the fractions to have a denominator of 6 (divide the numerators and denominators by 5)
= 1.2/6 , 5/6
divide the numerator 5 by 1.2 = 4.17
It will take 4.17 days to complete 5/6 of her project