What is the turning point of the blue parabola?

If the ratio of sum of the first m and n terms of an ap is m2 : n2 , show that the ratio of its mth and nth terms is (2m − 1) : (2n − 1).

Having a hard time understanding this question (see attachment).

Betty correctly answers 30 questions on your math test there are 40 questions on the test what percent of the questions did she answered incorrectly