Raeann had some $100-notes and some $10-notes.
27 of the-notes were $100-notes and the rest were $10-notes. After Raeann had spent $1000 worth of $10-notes and
12 of $100-notes, she had
79 of the notes left. Find the number of $100-notes Raeann had left.
| |
$100-notes |
$10-notes |
Total |
Comparing $100-notes
and $10-notes
at first |
2x9 =
18 u |
5x9 =
45 u |
7x9 =
63 u |
| Before |
2x9 =
18 u |
|
9x7 =
63 u |
| Change |
- 1x9 =
- 9 u |
- 100 |
- 2x7 =
- 14 u |
| After |
1x9=
9 u |
45 u - 100 |
7x7 =
49 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 7 and 9 is 63.
The number of $100-notes is repeated.
Number of $10-notes
= 1000 ÷ 10
= 100
Total number of notes spent = 9 u + 100
9 u + 100 = 14 u
14 u - 9 u = 100
5 u = 100
1 u = 100 ÷ 5 = 20
Number of $100-notes that Raeann had left
= 9 u
= 9 x 20
= 180
Answer(s): 180
