Fanny had some $5-notes and some $10-notes.
710 of the-notes were $5-notes and the rest were $10-notes. After Fanny had spent $2320 worth of $10-notes and
47 of $5-notes, she had
13 of the notes left. Find the number of $5-notes Fanny had left.
| |
$5-notes |
$10-notes |
Total |
Comparing $5-notes
and $10-notes
at first |
7x3 =
21 u |
3x3 =
9 u |
10x3 =
30 u |
| Before |
7x3 =
21 u |
|
3x10 =
30 u |
| Change |
- 4x3 =
- 12 u |
- 232 |
- 2x10 =
- 20 u |
| After |
3x3=
9 u |
9 u - 232 |
1x10 =
10 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 10 and 3 is 30.
The number of $5-notes is repeated.
Number of $10-notes
= 2320 ÷ 10
= 232
Total number of notes spent = 12 u + 232
12 u + 232 = 20 u
20 u - 12 u = 232
8 u = 232
1 u = 232 ÷ 8 = 29
Number of $5-notes that Fanny had left
= 9 u
= 9 x 29
= 261
Answer(s): 261
