Gabby had some $2-notes and some $5-notes.
311 of the-notes were $2-notes and the rest were $5-notes. After Gabby had spent $3150 worth of $5-notes and
23 of $2-notes, she had
37 of the notes left. Find the number of $2-notes Gabby had left.
|
$2-notes |
$5-notes |
Total |
Comparing $2-notes and $5-notes at first |
3x7 = 21 u |
8x7 = 56 u |
11x7 = 77 u |
Before |
3x7 = 21 u |
|
7x11 = 77 u |
Change |
- 2x7 = - 14 u |
- 630 |
- 4x11 = - 44 u |
After |
1x7= 7 u |
56 u - 630 |
3x11 = 33 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 11 and 7 is 77.
The number of $2-notes is repeated.
Number of $5-notes
= 3150 ÷ 5
= 630
Total number of notes spent = 14 u + 630
14 u + 630 = 44 u
44 u - 14 u = 630
30 u = 630
1 u = 630 ÷ 30 = 21
Number of $2-notes that Gabby had left
= 7 u
= 7 x 21
= 147
Answer(s): 147