My answer would be false. I hope this answers your question!
        
                    
             
        
        
        
470 miles in 2 hrs......470/2 = 235 per hr
in 12 hrs...
235 * 12 = 2820 miles <==
        
                    
             
        
        
        
It seems most likely that ...
... Samantha will save $37.50 because she must first find the 25% sale price before taking the extra 50% reduction
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In the real world, it seems probable that Samantha will be offered the choice of using the coupon <em>or</em> the sale discount. If she chooses tht 50% coupon, her savings will be $30. If she chooses the marked sale discount, her savings will be $15. 
The scenario above assumes she gets 50% off the sale price of $45, so saves $15+22.50 = $37.50 off the original price.