Lucy had some $10-notes and some $1-notes.
211 of the notes were $10-notes and the rest were $1-notes. After Lucy had spent $247 worth of $1-notes and
12 of $10-notes, she had
13 of the notes left. Find the number of $1-notes Lucy had left.
| |
$10-notes |
$1-notes |
Total |
Comparing $10-notes
and $1-notes
at first |
2x3 =
6 u |
9x3 =
27 u |
11x3 =
33 u |
| Before |
2x3 =
6 u |
|
3x11 =
33 u |
| Change |
- 1x3 =
- 3 u |
- 247 |
- 2x11 =
- 22 u |
| After |
1x3=
3 u |
27 u - 247 |
1x11 =
11 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 11 and 3 is 33.
The number of $10-notes is repeated.
Number of $1-notes
= 247 ÷ 1
= 247
Total number of notes spent = 3 u + 247
3 u + 247 = 22 u
22 u - 3 u = 247
19 u = 247
1 u = 247 ÷ 19 = 13
Number of $1-notes that Lucy had left
= 27 u - 247
= 27 x 13 - 247
= 104
Answer(s): 104
