Mary bought 7 laptops and 9 deep fryers. Each laptop costs $435 more than each deep fryer. She spent 20% of her money on the deep fryers.
- How much did each laptop cost?
- How much did she spend altogether?
| |
Laptops |
Deep fryers |
Total |
| Number |
7 |
9 |
|
| Value |
1 u + $435 |
1 u |
|
| Total value |
7 u + $3045 |
9 u |
|
Comparing amounts
spent on laptops
and deep fryers |
80%
|
20% |
100% |
(a)
Amount that Mary spent on the laptops
= 7(1 u + 435)
= 7 u + 3045
Amount that Mary spent on the deep fryers
= 9 x 1 u
= 9 u
Amount that Mary spent on the laptops in percent
= 100% - 20%
= 80%
20% → 9 u
80% → 4 x 9 u = 36 u
36 u = 7 u + 3045
36 u - 7 u = 3045
29 u = 3045
1 u = 3045 ÷ 29 = 105
Cost of each laptop
= 105 + 435
= $540
(b)
100% → 9 u + 36 u = 45 u
Amount that Mary spent altogether
= 45 u
= 45 x 105
= $4725
Answer(s): (a) $540; (b) $4725
