Picture attached. I keep getting an answer that isn’t an option. Can someone please help?

A. 210 cm^3
B. 180 cm^3
C. 240 cm^3
D. 150 cm^3

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).

Gabrielle's age is two times mikhail's age. the sum of their ages is 84. what is mikhail's age?

36x2 + 49y2 = 1,764 the foci are located at: (-√13, 0) and (√13,0) (0, -√13) and (0,√13) (-1, 0) and (1, 0)edit: the answer is (- the square root of 13, 0) and (the square root of 13, 0)