Elyse had some $5-notes and some $10-notes.
67 of the notes were $5-notes and the rest were $10-notes. After Elyse had spent $480 worth of $10-notes and
16 of $5-notes, she had
34 of the notes left. Find the number of $10-notes Elyse had left.
| |
$5-notes |
$10-notes |
Total |
Comparing $5-notes
and $10-notes
at first |
6x4 =
24 u |
1x4 =
4 u |
7x4 =
28 u |
| Before |
6x4 =
24 u |
|
4x7 =
28 u |
| Change |
- 1x4 =
- 4 u |
- 48 |
- 1x7 =
- 7 u |
| After |
5x4=
20 u |
4 u - 48 |
3x7 =
21 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 7 and 4 is 28.
The number of $5-notes is repeated.
Number of $10-notes
= 480 ÷ 10
= 48
Total number of notes spent = 4 u + 48
4 u + 48 = 7 u
7 u - 4 u = 48
3 u = 48
1 u = 48 ÷ 3 = 16
Number of $10-notes that Elyse had left
= 4 u - 48
= 4 x 16 - 48
= 16
Answer(s): 16
