(20 POINTS!) Keisha bought a new pair of skis for $450. She puts $120 down and got a student discount of $45. Her mother gave her 1/2 of the balance for her birthday. Which of these expressions could be used to find the amount Keisha still owes for the skis?
A) 450 - 120 + 45 ÷ 2 C) 450 - (120 - 45) ÷ 2
B) [450 - (120 - 45) ÷ 2] D) [450 - (120 + 45)] ÷ 2