PSLE
Kathy had two streamers of the same length. She cut the first streamer into equal parts of length 15 cm and to each part she tied 3 silver balls. After that, she cut the second streamer into equal parts of length 20 cm and to each part she tied 5 gold balls. When she finished tying, she counted that there were 6 more gold balls than silver balls. How many balls were there altogether?

	First streamer	Second streamer	Difference	Total
Length of each part	15 cm	20 cm
Number of balloons tied to each part	3 silver balloons	5 gold balloons
LCM	60 cm	60 cm
Number of equal parts	60 ÷ 15 = 4	60 ÷ 20 = 3
Number of balloons for each streamer per set	4 x 3 = 12	5 x 3 = 15	15 - 12 = 3	12 + 15 = 27

LCM of 15 and 20 = 60

Number of sets of 3 silver balls in a length of 60 cm
= 60 ÷ 15
= 4

Number of silver balls in a length of 60 cm
= 4 x 3
= 12

Number of sets of 5 gold balls in a length of 60 cm
= 60 ÷ 20
= 3

Number of gold balls in a length of 60 cm
= 3 x 5
= 15

Extra number of gold balls in a length of 60 cm
= 15 - 12
= 3

Number of sets of balls
= 6 ÷ 3
= 2

Total number of balls in one set of 60 cm of silver balloons and one set of 60 cm of gold balloons
= 12 + 15
= 27

Total number of balls of the two streamers
= 2 x 27
= 54

Answer(s): 54