PSLE
Lynn had two strings of the same length. She cut the first string into equal parts of length 40 cm and to each part she tied 2 green balloons. After that, she cut the second string into equal parts of length 60 cm and to each part she tied 4 pink balloons. When she finished tying, she counted that there were 10 more pink balloons than green balloons. How many balloons were there altogether?

	First string	Second string	Difference	Total
Length of each part	40 cm	60 cm
Number of balloons tied to each part	2 green balloons	4 pink balloons
LCM	120 cm	120 cm
Number of equal parts	120 ÷ 40 = 3	120 ÷ 60 = 2
Number of balloons for each string per set	3 x 2 = 6	4 x 2 = 8	8 - 6 = 2	6 + 8 = 14

LCM of 40 and 60 = 120

Number of sets of 2 green balloons in a length of 120 cm
= 120 ÷ 40
= 3

Number of green balloons in a length of 120 cm
= 3 x 2
= 6

Number of sets of 4 pink balloons in a length of 120 cm
= 120 ÷ 60
= 2

Number of pink balloons in a length of 120 cm
= 2 x 4
= 8

Extra number of pink balloons in a length of 120 cm
= 8 - 6
= 2

Number of sets of balloons
= 10 ÷ 2
= 5

Total number of balloons in one set of 120 cm of green balloons and one set of 120 cm of pink balloons
= 6 + 8
= 14

Total number of balloons of the two strings
= 5 x 14
= 70

Answer(s): 70