Answer:
$120
Step-by-step explanation:
The dealer's 20% profit amounted to ...
0.20 × $90 = $18
This means the discounted retail price was ...
$90 +18 = $108
This was 10% off the retail price, so was 90% of it.
$108 = 0.90 × retail price
$108/0.90 = $120 = retail price . . . . . divide by 0.90
The retail price of the answering machine was $120.