Winnie had a total of 18 pieces of $20 and $100 notes at first. She spent
47 of the number of $20 notes and received another 2 pieces of $100 notes from her mother. After that, the number of $100 notes she had was
12 of the remaining notes. How much money did Winnie have at first?
|
$20 |
$100 |
Total |
Before |
7 u |
3 u - 2 |
18 |
Change |
- 4 u |
+ 2 |
|
After |
3 u |
|
|
Comparing $20-notes and $100-notes |
1x3 = 3 u |
1x3 = 3 u |
|
The number of $20-notes and $100-notes in the end is the same.
The number of $20-notes in the end is repeated. Make the number of $20-notes in the end the same. LCM of 1 and 3 is 3.
Number of notes at first
= 7 u + 3 u - 2
= 10 u - 2
10 u - 2 = 18
10 u = 18 + 2
10 u = 20
1 u = 20 ÷ 10 = 2
Number of $20-notes at first
= 7 u
= 7 x 2
= 14
Total value of $20-notes at first
= 14 x 20
= $280
Number of $100-notes at first
= 3 u - 2
= 3 x 2 - 2
= 6 - 2
= 4
Total value of $100-notes at first
= 4 x 100
= $400
Amount that Winnie had at first
= 280 + 400
= $680
Answer(s): $680