At the end of February, Julie had thrice as many 10-cent coins as 50-cent coins in her piggy bank. She took out 75 10-cent coins and exchanged it for 50-cent coins of the same value. In March, she saved another 52 10-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 March?
| |
10-cent |
50-cent |
Total |
| Before |
3 u |
1 u |
|
| Change 1 |
- 75 |
+ 15 |
|
| Change 2 |
+ 52 |
+ ? |
|
| 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 10-cent in the end
= 1 p
= 100
Number of 10-cent at first
= 100 - 52 + 75
= 123
3 u = 123
1 u = 123 ÷ 3 = 41
Number of 50-cent coins in the end
= 4 p
= 4 x 100
= 400
Total value of 75 10-cent coins
= 75 x 10
= 750¢
Number of 50-cent coins that was exchanged from 75 10-cent coins
= 750 ÷ 50
= 15
Number of 50-cent coins that Julie saved in March
= 4 p - 1 u - 15
= 400 - 41 - 15
= 344
Answer(s): 344
