At the end of September, Linda had twice as many 10-cent coins as 50-cent coins in her piggy bank. She took out 55 10-cent coins and exchanged it for 50-cent coins of the same value. In October, she saved another 61 10-cent coins and some 50-cent coins. She then had twice as many 50-cent coins in the end. She had 270 coins in the end. How many 50-cent coins did she save in October?

	10-cent	50-cent	Total
Before	2 u	1 u
Change 1	- 55	+ 11
Change 2	+ 61	+ ?
After	1 p	2 p	270

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

3 p = 270

1 p = 270 ÷ 3 = 90

Number of 10-cent in the end
= 1 p
= 90

Number of 10-cent at first
= 90 - 61 + 55
= 84

2 u = 84

1 u = 84 ÷ 2 = 42

Number of 50-cent coins in the end
= 2 p
= 2 x 90
= 180

Total value of 55 10-cent coins 
= 55 x 10
= 550¢

Number of 50-cent coins that was exchanged from 55 10-cent coins 
= 550 ÷ 50
= 11

Number of 50-cent coins that Linda saved in October
= 2 p - 1 u - 11
= 180 - 42 - 11 
= 127 

Answer(s): 127