Irene had some $2-notes and some $10-notes.
56 of the-notes were $2-notes and the rest were $10-notes. After Irene had spent $1400 worth of $10-notes and
25 of $2-notes, she had
19 of the notes left. Find the number of $2-notes Irene had left.
| |
$2-notes |
$10-notes |
Total |
Comparing $2-notes
and $10-notes
at first |
5x3 =
15 u |
1x3 =
3 u |
6x3 =
18 u |
| Before |
5x3 =
15 u |
|
9x2 =
18 u |
| Change |
- 2x3 =
- 6 u |
- 140 |
- 8x2 =
- 16 u |
| After |
3x3=
9 u |
3 u - 140 |
1x2 =
2 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 6 and 9 is 18.
The number of $2-notes is repeated.
Number of $10-notes
= 1400 ÷ 10
= 140
Total number of notes spent = 6 u + 140
6 u + 140 = 16 u
16 u - 6 u = 140
10 u = 140
1 u = 140 ÷ 10 = 14
Number of $2-notes that Irene had left
= 9 u
= 9 x 14
= 126
Answer(s): 126
