You have towels of three sizes. The length of the first is 3 / 4 m, which makes up 3 / 5 of the length of the second. The length of the third towel is 5 / 12 of the sum of the lengths of the first two. What part of the third towel is the second?

9/10

Step-by-step explanation:

In ratio units, the relative lengths of the first, second, and third towels are ...

... 1 : 3/5 : (5/12) · (1 + 3/5)

... = 1 : 3/5 : 2/3

Then the fraction the second towel is of the third towel is ...

... (3/5) / (2/3) = (3/5) · (3/2) = 9/10