Answer:
The answer is $300.
Explanation:
The original price of the guitar is $600 and if we apply the 45% off, the final price of the guitar will be the 55% of its original price:
600*55%=

Then, the customer has a coupon for $30.00 off, so we have to subtract this coupon to the final cost of the guitar:
$330-$30=$300
Generally, first we have to apply the discount on the original price and the we can use the coupon.
Finally, the customer has to pay $300 for the guitar.