PSLE
A box contained gold and orange beads. At first, the number of gold beads was ¹₃ the number of orange beads. After ²₅ of the gold beads and ¹₁₀ of the orange beads were used, 330 beads were left.

1. What fraction of the beads were left? Leave your answer in the simplest form.
2. How many beads were used?

	Gold	Orange
Comparing gold beads and orange beads at first	1x10 = 10 u	3x10 = 30 u
Before	5x2 = 10 u	10x3 = 30 u
Change	- 2x2 =  - 4 u	- 1x3 = - 3 u
After	3x2 =  6 u	9x3 = 27 u

(a)
The number of orange beads at first is repeated. Make the number of orange beads at first the same. 
LCM of 3 and 10 is 30.

The number of gold beads at first is repeated.

Since the number of gold beads at first is 10 u, we make the total number of gold beads at first the same by multiplying 5 by 2 to become 10 u too.

Fraction of the beads left
= ^{6 + 27}_{10 + 30} 
= ³³₄₀

(b)
Number of beads left
= 6 u + 27 u
= 33 u

33 u = 330

1 u = 330 ÷ 33 = 10

Number of beads used
= 4 u + 3 u
= 7 u
= 7 x 10
= 70

Answer(s): (a) ³³₄₀; (b) 70