PSLE
Dana had two strings of the same length. She cut the first string into equal parts of length 70 cm and to each part she tied 3 grey heart cutouts. After that, she cut the second string into equal parts of length 100 cm and to each part she tied 5 yellow heart cutouts. When she finished tying, she counted that there were 20 more yellow heart cutouts than grey heart cutouts. How many heart cutouts were there altogether?

	First string	Second string	Difference	Total
Length of each part	70 cm	100 cm
Number of balloons tied to each part	3 grey balloons	5 yellow balloons
LCM	700 cm	700 cm
Number of equal parts	700 ÷ 70 = 10	700 ÷ 100 = 7
Number of balloons for each string per set	10 x 3 = 30	5 x 7 = 35	35 - 30 = 5	30 + 35 = 65

LCM of 70 and 100 = 700

Number of sets of 3 grey heart cutouts in a length of 700 cm
= 700 ÷ 70
= 10

Number of grey heart cutouts in a length of 700 cm
= 10 x 3
= 30

Number of sets of 5 yellow heart cutouts in a length of 700 cm
= 700 ÷ 100
= 7

Number of yellow heart cutouts in a length of 700 cm
= 7 x 5
= 35

Extra number of yellow heart cutouts in a length of 700 cm
= 35 - 30
= 5

Number of sets of heart cutouts
= 20 ÷ 5
= 4

Total number of heart cutouts in one set of 700 cm of grey balloons and one set of 700 cm of yellow balloons
= 30 + 35
= 65

Total number of heart cutouts of the two strings
= 4 x 65
= 260

Answer(s): 260