Fanny had some $50-notes and some $1-notes.
23 of the-notes were $50-notes and the rest were $1-notes. After Fanny had spent $100 worth of $1-notes and
12 of $50-notes, she had
37 of the notes left. Find the number of $50-notes Fanny had left.
| |
$50-notes |
$1-notes |
Total |
Comparing $50-notes
and $1-notes
at first |
2x7 =
14 u |
1x7 =
7 u |
3x7 =
21 u |
| Before |
2x7 =
14 u |
|
7x3 =
21 u |
| Change |
- 1x7 =
- 7 u |
- 100 |
- 4x3 =
- 12 u |
| After |
1x7=
7 u |
7 u - 100 |
3x3 =
9 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 3 and 7 is 21.
The number of $50-notes is repeated.
Number of $1-notes
= 100 ÷ 1
= 100
Total number of notes spent = 7 u + 100
7 u + 100 = 12 u
12 u - 7 u = 100
5 u = 100
1 u = 100 ÷ 5 = 20
Number of $50-notes that Fanny had left
= 7 u
= 7 x 20
= 140
Answer(s): 140
