Final answer:
To determine the coupon that gives the lower price, calculate the final price with each coupon. Coupon a gives a final price of $64.80, while coupon b gives a final price of $65.61.
Step-by-step explanation:
To determine the coupon that gives the lower price, we need to calculate the final price with each coupon.
For coupon a, which is 20% off of a $81 bicycle, we get a discount of 20% of $81, which is $16.20. So the final price with coupon a is $81 - $16.20 = $64.80.
For coupon b, which is a 19% rebate on a $81 bicycle, we get a rebate of 19% of $81, which is $15.39. So the final price with coupon b is $81 - $15.39 = $65.61.
Therefore, the coupon that gives the lower price is coupon a with a final price of $64.80.