Answer:

56 m

Step-by-step explanation:

I will assume that the ratio given in the question is 2:3:4 since 23:4 only covers two pieces.

We can think of this problem this way:

The 1st thread has a length of 2 parts of 126. The 2nd thread has a length of 3 parts of 126. The 3rd thread has 4 parts of 126.

We can find the total number of parts by adding them.

2+3+4=9

We can now find the exact length of 1 part of the thread by dividing.

126/9 = 14

Now, we multiply the quotient to each thread.

2×14 = 28

3×14 = 42

4×14 = 56

Among the three pieces, the length of the longest thread is 56 m .