Answer:
40cm
Explanation:
Piece of string is 64cm.
Divided in the ratio 1 : 2 : 5
Assuming 1x, 2x, and 5x as the pieces
Then,
⇒ 1x + 2x + 5x = 64
⇒ 8x = 64
⇒ 8x/8 = 64/8 [dividing both sides by 8]
⇒ x = 8
Henceforth, lenght of the longest piece would be 5x = 5(8) = 40cm