PSLE
Diana had two streamers of the same length. She cut the first streamer into equal parts of length 25 cm and to each part she tied 2 brown paper cranes. After that, she cut the second streamer into equal parts of length 40 cm and to each part she tied 5 red paper cranes. When she finished tying, she counted that there were 18 more red paper cranes than brown paper cranes. How many paper cranes were there altogether?

	First streamer	Second streamer	Difference	Total
Length of each part	25 cm	40 cm
Number of balloons tied to each part	2 brown balloons	5 red balloons
LCM	200 cm	200 cm
Number of equal parts	200 ÷ 25 = 8	200 ÷ 40 = 5
Number of balloons for each streamer per set	8 x 2 = 16	5 x 5 = 25	25 - 16 = 9	16 + 25 = 41

LCM of 25 and 40 = 200

Number of sets of 2 brown paper cranes in a length of 200 cm
= 200 ÷ 25
= 8

Number of brown paper cranes in a length of 200 cm
= 8 x 2
= 16

Number of sets of 5 red paper cranes in a length of 200 cm
= 200 ÷ 40
= 5

Number of red paper cranes in a length of 200 cm
= 5 x 5
= 25

Extra number of red paper cranes in a length of 200 cm
= 25 - 16
= 9

Number of sets of paper cranes
= 18 ÷ 9
= 2

Total number of paper cranes in one set of 200 cm of brown balloons and one set of 200 cm of red balloons
= 16 + 25
= 41

Total number of paper cranes of the two streamers
= 2 x 41
= 82

Answer(s): 82