a whole, is whatever/whatever.
so... he painted 4/5 of the house first..... now the whole house is 5/5, from 4/5 to 5/5 is just 1/5, so 1/5 was left for the next day.
the next day, he painted only 2/3 of what was left, what is 2/3 of 1/5? well is just their product.
