How do you derive the geometric series formula?

Let denote the th partial sum of a geometric sequence with common ratio . The sum of the first terms of the sequence is

.

Suppose we multiply both sides by , then



Taking the difference makes most of the terms vanish:




Then solving for gives the formula.

The answer is 270 cars.you can do this by making a proportional relationship. for instance, 200 is the whole we are using, so on a “number line” 200 would be over 100%. now, since he sells 35% more, add 35% to 100% to get 135% on the other side of the “number line” on the bottom half, leaving the top half empty.cross multiply 200 by 135 then divide by 100 to get your answer. i hope this , if it did, , if you don’t mind, giving me brainiest! 200/100% } 200 • 135 /100 ? /135%