PSLE
Shiyun had two strings of the same length. She cut the first string into equal parts of length 15 cm and to each part she tied 2 silver heart cutouts. After that, she cut the second string into equal parts of length 20 cm and to each part she tied 4 yellow heart cutouts. When she finished tying, she counted that there were 16 more yellow heart cutouts than silver heart cutouts. How many heart cutouts were there altogether?

	First string	Second string	Difference	Total
Length of each part	15 cm	20 cm
Number of balloons tied to each part	2 silver balloons	4 yellow balloons
LCM	60 cm	60 cm
Number of equal parts	60 ÷ 15 = 4	60 ÷ 20 = 3
Number of balloons for each string per set	4 x 2 = 8	4 x 3 = 12	12 - 8 = 4	8 + 12 = 20

LCM of 15 and 20 = 60

Number of sets of 2 silver heart cutouts in a length of 60 cm
= 60 ÷ 15
= 4

Number of silver heart cutouts in a length of 60 cm
= 4 x 2
= 8

Number of sets of 4 yellow heart cutouts in a length of 60 cm
= 60 ÷ 20
= 3

Number of yellow heart cutouts in a length of 60 cm
= 3 x 4
= 12

Extra number of yellow heart cutouts in a length of 60 cm
= 12 - 8
= 4

Number of sets of heart cutouts
= 16 ÷ 4
= 4

Total number of heart cutouts in one set of 60 cm of silver balloons and one set of 60 cm of yellow balloons
= 8 + 12
= 20

Total number of heart cutouts of the two strings
= 4 x 20
= 80

Answer(s): 80