Think of the original price of the coffeemaker as 100u

Since 30% = 30/100,

The discount given = 30u

Discounted price = 100u - 30u = 70u

Original price of microwave oven
= 100u + $320

Since 25% = 25/100,

Discount given = 25u + 25/100 x $320

Discounted price = 75u + 75/100 × $320

= 75u + ¾ x $320
= 75u + $240

Total amount paid = 70u + 75u + $240
= $443

145u + $240 = $443

145u = $443 - $240

145u = $203

1u = $203 ÷ 145 = $1.40

Usual price of the coffee maker = 100 × $1.40 = $140

Alternatively, let original price of coffee maker be 1u

Since 30% = 30/100 = 3/10 = 0.3

Discount = 0.3u

Discounted price = 1u - 0.3u = 0.7u


Original price of microwave oven
= 1u + $320

Since 25% = 25/100 = 1/4 = 0.25

Discount given = 0.25u + 0.25 x $320
= 0.25u + $80

Discounted price = 1u + $320 - 0.25u - $280
= 0.75u + $240

Total amount paid = 0.7u + 0.75u + $240
= $443

1.45u + $240 = $443

1.45u = $443 - $240

1.45u = $203

1u = $203 ÷ 1.45 = $140
(Original price of coffee maker)