Answer:
$450+$50= X
X=$500
Explanation:
The sale price is $450.00, so you take that amount and $50.00 which the amount he paid less and add them both. We do this because we want to see the original price of the computer. If it mentioned the original price already and the amount $50.00 and asked the sail price instead, we would have to subtract to get the answer.
Here we have to add.
450+50=500
(add the dollar sign)
$450+$50=X
X=$500