At the end of May, Esther had twice as many 20-cent coins as 50-cent coins in her piggy bank. She took out 85 20-cent coins and exchanged it for 50-cent coins of the same value. In June, she saved another 35 20-cent coins and some 50-cent coins. She then had twice as many 50-cent coins in the end. She had 120 coins in the end. How many 50-cent coins did she save in June?

	20-cent	50-cent	Total
Before	2 u	1 u
Change 1	- 85	+ 34
Change 2	+ 35	+ ?
After	1 p	2 p	120

Total number of coins in the end
= 1 p + 2 p 
= 3 p

3 p = 120

1 p = 120 ÷ 3 = 40

Number of 20-cent in the end
= 1 p
= 40

Number of 20-cent at first
= 40 - 35 + 85
= 90

2 u = 90

1 u = 90 ÷ 2 = 45

Number of 50-cent coins in the end
= 2 p
= 2 x 40
= 80

Total value of 85 20-cent coins 
= 85 x 20
= 1700¢

Number of 50-cent coins that was exchanged from 85 20-cent coins 
= 1700 ÷ 50
= 34

Number of 50-cent coins that Esther saved in June
= 2 p - 1 u - 34
= 80 - 45 - 34 
= 1 

Answer(s): 1