Answer:
- <em>The common ratio of the progression is 3/4</em>
Explanation:
A <em>geometric progression</em> is a sequence of terms in which the consecutive terms have a constant ratio; thus, each term is equal to the previous one multiplied by a constant value:

A<em> infinite geometric progression</em> may have a finite sum. When the absolute value of the ratio is less than 1, the sum of the infinite geometric progression has a finite value equal to:
Thus, the information given translates to:

Now you can solve for the constant ratio, r:

<span>There are different methods of subtraction. Break up the sum into different parts. 20 - 7 is 13. 0.39 - 0.60 requires borrowing 1 unit from the 13 to make 1.39 - 0.60. This makes 0.79. Add the two results together: 12 + 0.79 = 12.79.</span>
So for every gallon he can drive 50 miles. So I think the slope would be 50/-1
I believe the answer is 51,600 hope that helps!(: