PSLE
At first, Sarah had an equal number of black and silver marbles . She gave away ³₄ of her black marbles and some silver marbles. In the end, she was left with ³₅ of her marbles. What fraction of the silver marbles did Sarah give away?

	Black	Silver	Total
Comparing black marbles and silver marbles at first	1x4x5 = 20 u	1x4x5 =  20 u	2x4x5 =  40 u
Before	4x5 = 20 u	20 u	5x8 = 40 u
Change	- 3x5 = - 15 u	- 1 u	- 3x8 = - 16 u
After	1x5 = 5 u	19 u	2x8 = 24 u

After1_x5 =
5 u
19 u2_x8 =
24 u
The number of black marbles at first is repeated. Make the number of black marbles the first the same. LCM of 4 and 1 is 4.

The total number of marbles at first is repeated. Make the total number of marbles at first the same. LCM of 8 and 5 is 40.

Number of silver marbles that Sarah was left with
= 24 u - 5 u
= 19 u

Number of silver marbles that Sarah gave away
= 20 u - 19 u
= 1 u

Fraction of the silver marbles that Sarah gave away = ¹₂₀

Answer(s): ¹₂₀