Cindy had some $100-notes and some $2-notes.
67 of the-notes were $100-notes and the rest were $2-notes. After Cindy had spent $540 worth of $2-notes and
16 of $100-notes, she had
38 of the notes left. Find the number of $100-notes Cindy had left.
| |
$100-notes |
$2-notes |
Total |
Comparing $100-notes
and $2-notes
at first |
6x8 =
48 u |
1x8 =
8 u |
7x8 =
56 u |
| Before |
6x8 =
48 u |
|
8x7 =
56 u |
| Change |
- 1x8 =
- 8 u |
- 270 |
- 5x7 =
- 35 u |
| After |
5x8=
40 u |
8 u - 270 |
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 8 is 56.
The number of $100-notes is repeated.
Number of $2-notes
= 540 ÷ 2
= 270
Total number of notes spent = 8 u + 270
8 u + 270 = 35 u
35 u - 8 u = 270
27 u = 270
1 u = 270 ÷ 27 = 10
Number of $100-notes that Cindy had left
= 40 u
= 40 x 10
= 400
Answer(s): 400
