Rachel had some $5-notes and some $10-notes.
710 of the notes were $5-notes and the rest were $10-notes. After Rachel had spent $5130 worth of $10-notes and
37 of $5-notes, she had
511 of the notes left. Find the number of $10-notes Rachel had left.
| |
$5-notes |
$10-notes |
Total |
Comparing $5-notes
and $10-notes
at first |
7x11 =
77 u |
3x11 =
33 u |
10x11 =
110 u |
| Before |
7x11 =
77 u |
|
11x10 =
110 u |
| Change |
- 3x11 =
- 33 u |
- 513 |
- 6x10 =
- 60 u |
| After |
4x11=
44 u |
33 u - 513 |
5x10 =
50 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 10 and 11 is 110.
The number of $5-notes is repeated.
Number of $10-notes
= 5130 ÷ 10
= 513
Total number of notes spent = 33 u + 513
33 u + 513 = 60 u
60 u - 33 u = 513
27 u = 513
1 u = 513 ÷ 27 = 19
Number of $10-notes that Rachel had left
= 33 u - 513
= 33 x 19 - 513
= 114
Answer(s): 114
