Irene had some $2-notes and some $1-notes.
35 of the notes were $2-notes and the rest were $1-notes. After Irene had spent $384 worth of $1-notes and
13 of $2-notes, she had
49 of the notes left. Find the number of $1-notes Irene had left.
| |
$2-notes |
$1-notes |
Total |
Comparing $2-notes
and $1-notes
at first |
3x9 =
27 u |
2x9 =
18 u |
5x9 =
45 u |
| Before |
3x9 =
27 u |
|
9x5 =
45 u |
| Change |
- 1x9 =
- 9 u |
- 384 |
- 5x5 =
- 25 u |
| After |
2x9=
18 u |
18 u - 384 |
4x5 =
20 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 5 and 9 is 45.
The number of $2-notes is repeated.
Number of $1-notes
= 384 ÷ 1
= 384
Total number of notes spent = 9 u + 384
9 u + 384 = 25 u
25 u - 9 u = 384
16 u = 384
1 u = 384 ÷ 16 = 24
Number of $1-notes that Irene had left
= 18 u - 384
= 18 x 24 - 384
= 48
Answer(s): 48
