Carl had a total of 160 notes. The notes are $2 notes and $10 notes. After he spent 90% of the $2 notes and 80% of the $10 notes on one microwave oven, he was left with 2 times as many $10 notes as $2 notes. How much did the microwave oven cost?
|
$2 |
$10 |
Before |
10x1 = 10 u |
5x2 = 10 u
|
Change |
- 9x1 = - 9 u |
- 4x2 = - 8 u
|
After |
1x1 = 1 u |
1x2 = 2 u |
Comparing $2 and $10 in the end |
1x1 = 1 u
|
2x1 = 2 u |
90% of $2 notes =
90
100 of $2 notes =
910 of $2 notes
80% of $10 notes =
80100 of $10 notes =
45 of $10 notes
The number of $2 notes in the end is repeated. Make the number of $2 notes the same. LCM of 1 and 2 is 2.
The number of $10 notes in the end is repeated. Make the number of $10 notes the same. LCM of 1 and 1 is 1.
Number of notes at first
= 10 u + 10 u
= 20 u
20 u = 160
1 u = 160 ÷ 20 = 8
|
$2 |
$10 |
Number |
9 u |
8 u |
Value |
2 |
10 |
Total value |
18 u |
80 u |
Value of $2 spent
= 9 u x 2
= 18 u
Value of $10 spent
= 8 u x 10
= 80 u
Price of the microwave oven
= 18 u + 80 u
= 98 u
= 98 x 8
= $784
Answer(s): $784