Sabrina had some $50-notes and some $10-notes.
712 of the notes were $50-notes and the rest were $10-notes. After Sabrina had spent $630 worth of $10-notes and
67 of $50-notes, she had
38 of the notes left. Find the number of $10-notes Sabrina had left.
| |
$50-notes |
$10-notes |
Total |
Comparing $50-notes
and $10-notes
at first |
7x2 =
14 u |
5x2 =
10 u |
12x2 =
24 u |
| Before |
7x2 =
14 u |
|
8x3 =
24 u |
| Change |
- 6x2 =
- 12 u |
- 63 |
- 5x3 =
- 15 u |
| After |
1x2=
2 u |
10 u - 63 |
3x3 =
9 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 12 and 8 is 24.
The number of $50-notes is repeated.
Number of $10-notes
= 630 ÷ 10
= 63
Total number of notes spent = 12 u + 63
12 u + 63 = 15 u
15 u - 12 u = 63
3 u = 63
1 u = 63 ÷ 3 = 21
Number of $10-notes that Sabrina had left
= 10 u - 63
= 10 x 21 - 63
= 147
Answer(s): 147
