PSLE
Ivory had two streamers of the same length. She cut the first streamer into equal parts of length 80 cm and to each part she tied 3 grey paper cranes. After that, she cut the second streamer into equal parts of length 90 cm and to each part she tied 4 gold paper cranes. When she finished tying, she counted that there were 15 more gold paper cranes than grey paper cranes. How many paper cranes were there altogether?

	First streamer	Second streamer	Difference	Total
Length of each part	80 cm	90 cm
Number of balloons tied to each part	3 grey balloons	4 gold balloons
LCM	720 cm	720 cm
Number of equal parts	720 ÷ 80 = 9	720 ÷ 90 = 8
Number of balloons for each streamer per set	9 x 3 = 27	4 x 8 = 32	32 - 27 = 5	27 + 32 = 59

LCM of 80 and 90 = 720

Number of sets of 3 grey paper cranes in a length of 720 cm
= 720 ÷ 80
= 9

Number of grey paper cranes in a length of 720 cm
= 9 x 3
= 27

Number of sets of 4 gold paper cranes in a length of 720 cm
= 720 ÷ 90
= 8

Number of gold paper cranes in a length of 720 cm
= 8 x 4
= 32

Extra number of gold paper cranes in a length of 720 cm
= 32 - 27
= 5

Number of sets of paper cranes
= 15 ÷ 5
= 3

Total number of paper cranes in one set of 720 cm of grey balloons and one set of 720 cm of gold balloons
= 27 + 32
= 59

Total number of paper cranes of the two streamers
= 3 x 59
= 177

Answer(s): 177