One twentieth = one tenth, three fifteenth, two tenth = one fifth; That's equivalent to one tenth compared with one fifth, one tenth compared with one fifth = one twentieth compared with one fortieth, and the maximum should be one fifth.

Divided by one quarter, one fifth and two sevenths, = 145%, 148% and 140%, so two sevenths is the largest.

The denominator plus 24 = 32 is equivalent to four times the denominator, so the numerator should also be expanded by four times.

2 plus 2/9 = 20/9; Twenty-one; Find the numerator is two, multiply nine times three = twenty-seven, and find the denominator, and the result is two-sevenths.