Fanny had some $2-notes and some $5-notes.
710 of the-notes were $2-notes and the rest were $5-notes. After Fanny had spent $715 worth of $5-notes and
27 of $2-notes, she had
712 of the notes left. Find the number of $2-notes Fanny had left.
| |
$2-notes |
$5-notes |
Total |
Comparing $2-notes
and $5-notes
at first |
7x6 =
42 u |
3x6 =
18 u |
10x6 =
60 u |
| Before |
7x6 =
42 u |
|
12x5 =
60 u |
| Change |
- 2x6 =
- 12 u |
- 143 |
- 5x5 =
- 25 u |
| After |
5x6=
30 u |
18 u - 143 |
7x5 =
35 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 10 and 12 is 60.
The number of $2-notes is repeated.
Number of $5-notes
= 715 ÷ 5
= 143
Total number of notes spent = 12 u + 143
12 u + 143 = 25 u
25 u - 12 u = 143
13 u = 143
1 u = 143 ÷ 13 = 11
Number of $2-notes that Fanny had left
= 30 u
= 30 x 11
= 330
Answer(s): 330
