Marion bought 6 washing machines and 9 water heaters. Each washing machine costs $420 more than each water heater. She spent 20% of her money on the water heaters.
- How much did each washing machine cost?
- How much did she spend altogether?
| |
Washing machines |
Water heaters |
Total |
| Number |
6 |
9 |
|
| Value |
1 u + $420 |
1 u |
|
| Total value |
6 u + $2520 |
9 u |
|
Comparing amounts
spent on washing machines
and water heaters |
80%
|
20% |
100% |
(a)
Amount that Marion spent on the washing machines
= 6(1 u + 420)
= 6 u + 2520
Amount that Marion spent on the water heaters
= 9 x 1 u
= 9 u
Amount that Marion spent on the washing machines in percent
= 100% - 20%
= 80%
20% → 9 u
80% → 4 x 9 u = 36 u
36 u = 6 u + 2520
36 u - 6 u = 2520
30 u = 2520
1 u = 2520 ÷ 30 = 84
Cost of each washing machine
= 84 + 420
= $504
(b)
100% → 9 u + 36 u = 45 u
Amount that Marion spent altogether
= 45 u
= 45 x 84
= $3780
Answer(s): (a) $504; (b) $3780
