Sarah had some $100-notes and some $1-notes.
45 of the-notes were $100-notes and the rest were $1-notes. After Sarah had spent $105 worth of $1-notes and
34 of $100-notes, she had
16 of the notes left. Find the number of $100-notes Sarah had left.
| |
$100-notes |
$1-notes |
Total |
Comparing $100-notes
and $1-notes
at first |
4x6 =
24 u |
1x6 =
6 u |
5x6 =
30 u |
| Before |
4x6 =
24 u |
|
6x5 =
30 u |
| Change |
- 3x6 =
- 18 u |
- 105 |
- 5x5 =
- 25 u |
| After |
1x6=
6 u |
6 u - 105 |
1x5 =
5 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 5 and 6 is 30.
The number of $100-notes is repeated.
Number of $1-notes
= 105 ÷ 1
= 105
Total number of notes spent = 18 u + 105
18 u + 105 = 25 u
25 u - 18 u = 105
7 u = 105
1 u = 105 ÷ 7 = 15
Number of $100-notes that Sarah had left
= 6 u
= 6 x 15
= 90
Answer(s): 90
