Question

Your friend gave you a gift card for your birthday. You use it to buy a DVD for $15. The gift card balance shown on the receipt after the purchase is $45. What was the original value of the gift card?

Answer 1

x = Original value
x - 15 = 45
If we work backwards and add the cost of the DVD
$45 + $15 = $60

Answer 2

All you have to do is the inverse operation. And since the starting operation is subtraction, you would use addition.

  $15
+$45
_______
  $60

Your final answer would be $60.