The ratio of the number of $5-notes to $10-notes in Xylia's jar was 1 : 4. Xylia exchanged 9 pieces of $10-notes for $5-notes. She then had an equal number of $5-notes and $10-notes. What was the total value of $5-notes and $10-notes in Xylia's jar at first?
|
$5-notes |
$10-notes |
Before |
1 u |
4 u |
Change |
+ 18 |
- 9 |
After |
1 u + 18 |
4 u - 9 |
Value of 9 pieces of $10-notes
= 9 x 10
= $90
Number of $5-notes that Xylia exchanged for
= 90 ÷ 5
= 18
After the exchange, Xylia had an equal number of $5-notes and $10-notes.
4 u - 9 = 1 u + 18
4 u - 1 u = 18 + 9
3 u = 27
1 u = 27 ÷ 3 = 9
Number of $5-notes at first
= 1 u
= 9
Value of $5-notes at first
= 9 x 5
= $45
Number of $10-notes at first
= 4 u
= 4 x 9
= 36
Value of $10-notes at first
= 36 x 10
= $360
Total value of $5-notes and $10-notes at first
= 45 + 360
= $405
Answer(s): $405