15. 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:

dont understand

step-by-step explanation:

x = -4

step-by-step explanation:

- 20 - 4(x + 3) = 4x

=> -20 - 4x - 12 = 4x

=> - 32 -4x = 4x

=> -32 = 4x + 4x

=> - 32 = 8x

=> -32/8 = x

=> -4 = x