Seven days ago, the gas tank on Rosa's car was filled with 20 gallons of gasoline. Today there are 6 gallons of gasoline. a. What integer represents the change of gasoline in the past seven days? b. What is the mean change in gasoline in gallons per day? c. What is the fuel efficiency, in miles per gallon, of Rosa's car if she drove 490 miles in the past seven days?

-14 gallons. Given : Seven days ago, the gas tank on Roses car was filled with 20 gallons of gasoline. Today there are 6 gallons of gasoline. ∵ 20> 6 , it means there is decrease in the amount gasoline.

Step-by-step explanation:

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54 km / hours

step-by-step explanation:

we need to convert seconds to hours

60 seconds = 1 minutes

60 minutes = 1hour

15 m         60 second   60 minutes

  * *         = 54000 meters/ hour

second     1 minute             1 hour

now we need to convert meters to km

1000 m = 1 km

54000 m       1 km

*   = 54 km / hours

hour               1000m