Zara had some $2-notes and some $5-notes.
311 of the-notes were $2-notes and the rest were $5-notes. After Zara had spent $1500 worth of $5-notes and
23 of $2-notes, she had
37 of the notes left. Find the number of $2-notes Zara 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 |
- 300 |
- 4x11 =
- 44 u |
| After |
1x7=
7 u |
56 u - 300 |
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
= 1500 ÷ 5
= 300
Total number of notes spent = 14 u + 300
14 u + 300 = 44 u
44 u - 14 u = 300
30 u = 300
1 u = 300 ÷ 30 = 10
Number of $2-notes that Zara had left
= 7 u
= 7 x 10
= 70
Answer(s): 70
