Xylia had some $100-notes and some $10-notes.
89 of the-notes were $100-notes and the rest were $10-notes. After Xylia had spent $1980 worth of $10-notes and
58 of $100-notes, she had
15 of the notes left. Find the number of $100-notes Xylia had left.
| |
$100-notes |
$10-notes |
Total |
Comparing $100-notes
and $10-notes
at first |
8x5 =
40 u |
1x5 =
5 u |
9x5 =
45 u |
| Before |
8x5 =
40 u |
|
5x9 =
45 u |
| Change |
- 5x5 =
- 25 u |
- 198 |
- 4x9 =
- 36 u |
| After |
3x5=
15 u |
5 u - 198 |
1x9 =
9 u |
The total number of notes at first is the repeated. Make the total number of notes the same. LCM of 9 and 5 is 45.
The number of $100-notes is repeated.
Number of $10-notes
= 1980 ÷ 10
= 198
Total number of notes spent = 25 u + 198
25 u + 198 = 36 u
36 u - 25 u = 198
11 u = 198
1 u = 198 ÷ 11 = 18
Number of $100-notes that Xylia had left
= 15 u
= 15 x 18
= 270
Answer(s): 270
