Answer:
$100
Step-by-step explanation:
We know that the total cost was $110 and that the phone is $100 more than the case. With this, we can figure out how much the case is, and use that information to find the price of the phone.
Case price = total price - 100
= 110 - 100
Case price = 10
Now that we know that the case price is $10, we can figure out the phone's price.
Phone price = total price - case price
= 110 - 10
= 100
The phone costs $100
