Kathy had some $100-notes and some $1-notes.
56 of the notes were $100-notes and the rest were $1-notes. After Kathy had spent $28 worth of $1-notes and
45 of $100-notes, she had
29 of the notes left. Find the number of $1-notes Kathy had left.
| |
$100-notes |
$1-notes |
Total |
Comparing $100-notes
and $1-notes
at first |
5x3 =
15 u |
1x3 =
3 u |
6x3 =
18 u |
| Before |
5x3 =
15 u |
|
9x2 =
18 u |
| Change |
- 4x3 =
- 12 u |
- 28 |
- 7x2 =
- 14 u |
| After |
1x3=
3 u |
3 u - 28 |
2x2 =
4 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 6 and 9 is 18.
The number of $100-notes is repeated.
Number of $1-notes
= 28 ÷ 1
= 28
Total number of notes spent = 12 u + 28
12 u + 28 = 14 u
14 u - 12 u = 28
2 u = 28
1 u = 28 ÷ 2 = 14
Number of $1-notes that Kathy had left
= 3 u - 28
= 3 x 14 - 28
= 14
Answer(s): 14
