At the end of April, Tina had twice as many 20-cent coins as 50-cent coins in her piggy bank. She took out 60 20-cent coins and exchanged it for 50-cent coins of the same value. In May, she saved another 92 20-cent coins and some 50-cent coins. She then had four times as many 50-cent coins in the end. She had 500 coins in the end. How many 50-cent coins did she save in May?
|
20-cent |
50-cent |
Total |
Before |
2 u |
1 u |
|
Change 1 |
- 60 |
+ 24 |
|
Change 2 |
+ 92 |
+ ? |
|
After |
1 p |
4 p |
500 |
Total number of coins in the end
= 1 p + 4 p
= 5 p
5 p = 500
1 p = 500 ÷ 5 = 100
Number of 20-cent in the end
= 1 p
= 100
Number of 20-cent at first
= 100 - 92 + 60
= 68
2 u = 68
1 u = 68 ÷ 2 = 34
Number of 50-cent coins in the end
= 4 p
= 4 x 100
= 400
Total value of 60 20-cent coins
= 60 x 20
= 1200¢
Number of 50-cent coins that was exchanged from 60 20-cent coins
= 1200 ÷ 50
= 24
Number of 50-cent coins that Tina saved in May
= 4 p - 1 u - 24
= 400 - 34 - 24
= 342
Answer(s): 342