PSLE
Tiffany had two strings of the same length. She cut the first string into equal parts of length 35 cm and to each part she tied 4 gold paper cranes. After that, she cut the second string into equal parts of length 40 cm and to each part she tied 5 black paper cranes. When she finished tying, she counted that there were 15 more black paper cranes than gold paper cranes. How many paper cranes were there altogether?

	First string	Second string	Difference	Total
Length of each part	35 cm	40 cm
Number of balloons tied to each part	4 gold balloons	5 black balloons
LCM	280 cm	280 cm
Number of equal parts	280 ÷ 35 = 8	280 ÷ 40 = 7
Number of balloons for each string per set	8 x 4 = 32	5 x 7 = 35	35 - 32 = 3	32 + 35 = 67

LCM of 35 and 40 = 280

Number of sets of 4 gold paper cranes in a length of 280 cm
= 280 ÷ 35
= 8

Number of gold paper cranes in a length of 280 cm
= 8 x 4
= 32

Number of sets of 5 black paper cranes in a length of 280 cm
= 280 ÷ 40
= 7

Number of black paper cranes in a length of 280 cm
= 7 x 5
= 35

Extra number of black paper cranes in a length of 280 cm
= 35 - 32
= 3

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

Total number of paper cranes in one set of 280 cm of gold balloons and one set of 280 cm of black balloons
= 32 + 35
= 67

Total number of paper cranes of the two strings
= 5 x 67
= 335

Answer(s): 335