At the end of November, Jade had twice as many 20-cent coins as 50-cent coins in her piggy bank. She took out 65 20-cent coins and exchanged it for 50-cent coins of the same value. In December, she saved another 29 20-cent coins and some 50-cent coins. She then had four times as many 50-cent coins in the end. She had 250 coins in the end. How many 50-cent coins did she save in December?

	20-cent	50-cent	Total
Before	2 u	1 u
Change 1	- 65	+ 26
Change 2	+ 29	+ ?
After	1 p	4 p	250

Total number of coins in the end
= 1 p + 4 p 
= 5 p

5 p = 250

1 p = 250 ÷ 5 = 50

Number of 20-cent in the end
= 1 p
= 50

Number of 20-cent at first
= 50 - 29 + 65
= 86

2 u = 86

1 u = 86 ÷ 2 = 43

Number of 50-cent coins in the end
= 4 p
= 4 x 50
= 200

Total value of 65 20-cent coins 
= 65 x 20
= 1300¢

Number of 50-cent coins that was exchanged from 65 20-cent coins 
= 1300 ÷ 50
= 26

Number of 50-cent coins that Jade saved in December
= 4 p - 1 u - 26
= 200 - 43 - 26 
= 131 

Answer(s): 131