In an envelope, there were a total of 90 notes. 80% of them were $10-notes. The rest were $5-notes. Cole took out some $10-notes. As a result, the remaining $10-notes made up 10% of the notes left in the envelope. Find the total value of the $10-notes Cole took out from the envelope.
| |
$10 |
$5 |
Total |
| Before |
4x9 =
36 u |
1x9 =
9 u |
5x9 =
45 u |
| Change |
- ? |
|
|
| After |
1x1 =
1 u |
9x1 =
9 u |
10x1 =
10 u |
80% =
80100 =
45
10% =
10100 =
110
The number of $5-notes remains unchanged. Make the number of $5-notes the same. LCM of 1 and 9 is 9.
Total number of notes at first = 45 u
45 u = 90
1 u = 90 ÷ 45 = 2
Number of $10-notes that Cole took out from the envelope
= 36 u - 1 u
= 35 u
= 35 x 2
= 70
Total value of $10-notes taken out
= 70 x 10
= $700
Answer(s): $700
