PSLE
Lynn had two streamers of the same length. She cut the first streamer into equal parts of length 80 cm and to each part she tied 2 black balls. After that, she cut the second streamer into equal parts of length 100 cm and to each part she tied 3 blue balls. When she finished tying, she counted that there were 10 more blue balls than black balls. How many balls were there altogether?

	First streamer	Second streamer	Difference	Total
Length of each part	80 cm	100 cm
Number of balloons tied to each part	2 black balloons	3 blue balloons
LCM	400 cm	400 cm
Number of equal parts	400 ÷ 80 = 5	400 ÷ 100 = 4
Number of balloons for each streamer per set	5 x 2 = 10	3 x 4 = 12	12 - 10 = 2	10 + 12 = 22

LCM of 80 and 100 = 400

Number of sets of 2 black balls in a length of 400 cm
= 400 ÷ 80
= 5

Number of black balls in a length of 400 cm
= 5 x 2
= 10

Number of sets of 3 blue balls in a length of 400 cm
= 400 ÷ 100
= 4

Number of blue balls in a length of 400 cm
= 4 x 3
= 12

Extra number of blue balls in a length of 400 cm
= 12 - 10
= 2

Number of sets of balls
= 10 ÷ 2
= 5

Total number of balls in one set of 400 cm of black balloons and one set of 400 cm of blue balloons
= 10 + 12
= 22

Total number of balls of the two streamers
= 5 x 22
= 110

Answer(s): 110