Nora and Sabrina had 858 erasers altogether. They decided to play a game. In the first round, Sabrina lost 65 erasers to Nora. In the second round, Nora lost 33 erasers to Sabrina. At the end of the two rounds, Sabrina had twice as many erasers as Nora.

1. How many erasers did Nora have in the end?
2. How many erasers did Sabrina have at the beginning of the game?

	Nora	Sabrina	Total
Before	1 u + 33 - 65	2 u - 33 + 65	858
Round 1	+ 65	- 65
Round 2	- 33	+ 33
After	1 u	2 u	858

(a)
Total number of erasers
= 1 u + 2 u
= 3 u

3 u = 858

1 u = 858 ÷ 3 = 286

Number of erasers that Nora had in the end
= 1 u
= 286

(b)
Working backwards.

Number of erasers that Sabrina had at the end of round 2
= 2 u
= 2 x 286
= 572

Number of erasers that Sabrina had at the end of round 1
= 572 - 33
= 539

Number of erasers that Sabrina had at the beginning of the game
= 539 + 65
= 604

Answer(s): (a) 286; (b) 604