Carl had a total of 145 notes. The notes are $10 notes and $2 notes. After he spent 75% of the $10 notes and 80% of the $2 notes on one microwave oven, he was left with 5 times as many $2 notes as $10 notes. How much did the microwave oven cost?
|
$10 |
$2 |
Before |
4x1 = 4 u |
5x5 = 25 u
|
Change |
- 3x1 = - 3 u |
- 4x5 = - 20 u
|
After |
1x1 = 1 u |
1x5 = 5 u |
Comparing $10 and $2 in the end |
1x1 = 1 u
|
5x1 = 5 u |
75% of $10 notes =
75
100 of $10 notes =
34 of $10 notes
80% of $2 notes =
80100 of $2 notes =
45 of $2 notes
The number of $10 notes in the end is repeated. Make the number of $10 notes the same. LCM of 1 and 5 is 5.
The number of $2 notes in the end is repeated. Make the number of $2 notes the same. LCM of 1 and 1 is 1.
Number of notes at first
= 4 u + 25 u
= 29 u
29 u = 145
1 u = 145 ÷ 29 = 5
|
$10 |
$2 |
Number |
3 u |
20 u |
Value |
10 |
2 |
Total value |
30 u |
40 u |
Value of $10 spent
= 3 u x 10
= 30 u
Value of $2 spent
= 20 u x 2
= 40 u
Price of the microwave oven
= 30 u + 40 u
= 70 u
= 70 x 5
= $350
Answer(s): $350