To find the midpoint you find the average x and the average y values. The average of 1 and 9 is 5, and the average of 4 and 16 is 10. The midpoint would be (5,10).
∵ ΔSRQ is a right triangle
and RT⊥SQ
∴ x² = ST * TQ
∴ x² = 9 *16 = 144
∴ x = √144 = 12
You aren’t giving any context to the question
I’m not sure but is it C? I’m so sorry if it’s wrong