Answer:
It is arithmetic and it has a common difference of -99
3 tens= 30
7 tenths= 0.7
8 hundredths= 0.08
so 30+ 0.7+0.08= 30.78
With $17.50 she can get 11 2/3 gallons. 11 (she just got) + 8 (that she had) = 19 gallons. 19 x 27 MPG = 513 Miles.
27 divided by 3 = 9 (9 is a third of the MPG) 9 x 2 (since it was 2 thirds that were left) = 18
In total she can drive 531 miles.
