This is the image the points form, if you know your quadrilaterals, this should make it easier to picture and label. Need any further explanation?
I had this same question. The answer is b. 15,299.
hope this helps.
Answer: In khan academy, the answer is Replace one equation with sum/difference of both equations.
75% of the numbers lie below or on the third quartile, and the remaining 25% lie on or above it.
Well there is no exact answer