PSLE
Abi had two ribbons of the same length. She cut the first ribbon into equal parts of length 60 cm and to each part she tied 2 black balloons. After that, she cut the second ribbon into equal parts of length 100 cm and to each part she tied 5 green balloons. When she finished tying, she counted that there were 25 more green balloons than black balloons. How many balloons were there altogether?

	First ribbon	Second ribbon	Difference	Total
Length of each part	60 cm	100 cm
Number of balloons tied to each part	2 black balloons	5 green balloons
LCM	300 cm	300 cm
Number of equal parts	300 ÷ 60 = 5	300 ÷ 100 = 3
Number of balloons for each ribbon per set	5 x 2 = 10	5 x 3 = 15	15 - 10 = 5	10 + 15 = 25

LCM of 60 and 100 = 300

Number of sets of 2 black balloons in a length of 300 cm
= 300 ÷ 60
= 5

Number of black balloons in a length of 300 cm
= 5 x 2
= 10

Number of sets of 5 green balloons in a length of 300 cm
= 300 ÷ 100
= 3

Number of green balloons in a length of 300 cm
= 3 x 5
= 15

Extra number of green balloons in a length of 300 cm
= 15 - 10
= 5

Number of sets of balloons
= 25 ÷ 5
= 5

Total number of balloons in one set of 300 cm of black balloons and one set of 300 cm of green balloons
= 10 + 15
= 25

Total number of balloons of the two ribbons
= 5 x 25
= 125

Answer(s): 125