Winnie had some $100-notes and some $10-notes.
38 of the notes were $100-notes and the rest were $10-notes. After Winnie had spent $3740 worth of $10-notes and
23 of $100-notes, she had
49 of the notes left. Find the number of $10-notes Winnie had left.
| |
$100-notes |
$10-notes |
Total |
Comparing $100-notes
and $10-notes
at first |
3x9 =
27 u |
5x9 =
45 u |
8x9 =
72 u |
| Before |
3x9 =
27 u |
|
9x8 =
72 u |
| Change |
- 2x9 =
- 18 u |
- 374 |
- 5x8 =
- 40 u |
| After |
1x9=
9 u |
45 u - 374 |
4x8 =
32 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 8 and 9 is 72.
The number of $100-notes is repeated.
Number of $10-notes
= 3740 ÷ 10
= 374
Total number of notes spent = 18 u + 374
18 u + 374 = 40 u
40 u - 18 u = 374
22 u = 374
1 u = 374 ÷ 22 = 17
Number of $10-notes that Winnie had left
= 45 u - 374
= 45 x 17 - 374
= 391
Answer(s): 391
