4x^2 -28c + 40 = 1
-28c = 1 -4x^2 -40
-28c = -39 -4x^2
c = 39/28 + 4/28x^2
c = 39/28 + 1/7x^2 => answer
Since 1/100 is 1% or 0.01, then 0.9 is 90/100 or 90%. 0.907 is 907/1000 (we simply have the number and do 10^(numbers in the number after the decimal) for the denominator). or 90.7% (we have a decimal because it wouldn't make sense for it to be more than 1, but we know that it's not less than 90%
Mrs. Walters: 14.4 miles per gallon
Mr. Walters: 15 miles per gallon
Mr. Walters is getting the better mileage per gallon.
