Alexa bought a pair of skis for dollar 450. she made a payment of dollar 120 and caught a student discount of dollar 40. her mother paid half of the balance. how much does alexa i have left to pay?

If Alexa's mom paid 1/2 of the $450:
$65

if Alexa's mom paid 1/2 of the remaining price:
$145

Alexa's mom paying 1/2 the $450:

$450 divided by 2 = $225
$225 - $120 = $105
$105 - $40 = $65
Alexa has $65 left to pay

Alexa's mom paying 1/2 of the remaining price after the student discount and Alexa payed $120:

$450 - $120 = $330
$330 - $40 = $290
$290 divided by 2 = $145

(hope this helped )