Find the sum of the arithmetic series for which a_1 = 7, n = 31, and a_n = 127.

2077

There are 31 terms.

S₃₁ = 31(a₁+a₃₁)/2 = 31(7+127)/2 = 2077

twenty-six miles over two gallons because the proportion for the original 13 miles to one gallon would be written 13/1 and, doing the same thing to the top and bottom, i multiplied by 2 and got 26/2