Diana had some $2-notes and some $10-notes.
35 of the notes were $2-notes and the rest were $10-notes. After Diana had spent $4420 worth of $10-notes and
23 of $2-notes, she had
29 of the notes left. Find the number of $10-notes Diana had left.
| |
$2-notes |
$10-notes |
Total |
Comparing $2-notes
and $10-notes
at first |
3x9 =
27 u |
2x9 =
18 u |
5x9 =
45 u |
| Before |
3x9 =
27 u |
|
9x5 =
45 u |
| Change |
- 2x9 =
- 18 u |
- 442 |
- 7x5 =
- 35 u |
| After |
1x9=
9 u |
18 u - 442 |
2x5 =
10 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 5 and 9 is 45.
The number of $2-notes is repeated.
Number of $10-notes
= 4420 ÷ 10
= 442
Total number of notes spent = 18 u + 442
18 u + 442 = 35 u
35 u - 18 u = 442
17 u = 442
1 u = 442 ÷ 17 = 26
Number of $10-notes that Diana had left
= 18 u - 442
= 18 x 26 - 442
= 26
Answer(s): 26
