Opal had some $2-notes and some $5-notes.
710 of the notes were $2-notes and the rest were $5-notes. After Opal had spent $1160 worth of $5-notes and
67 of $2-notes, she had
27 of the notes left. Find the number of $5-notes Opal had left.
| |
$2-notes |
$5-notes |
Total |
Comparing $2-notes
and $5-notes
at first |
7x7 =
49 u |
3x7 =
21 u |
10x7 =
70 u |
| Before |
7x7 =
49 u |
|
7x10 =
70 u |
| Change |
- 6x7 =
- 42 u |
- 232 |
- 5x10 =
- 50 u |
| After |
1x7=
7 u |
21 u - 232 |
2x10 =
20 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 10 and 7 is 70.
The number of $2-notes is repeated.
Number of $5-notes
= 1160 ÷ 5
= 232
Total number of notes spent = 42 u + 232
42 u + 232 = 50 u
50 u - 42 u = 232
8 u = 232
1 u = 232 ÷ 8 = 29
Number of $5-notes that Opal had left
= 21 u - 232
= 21 x 29 - 232
= 377
Answer(s): 377
