If the distance from R to S is only half then the other half is S to T. The distance between R and S is (5,2). that should give you the answer
(n + 7)2 = n - 1
2n +14 = n - 1
2n - n +14 = n - n - 1
n + 14 -14 = -1 - 14
n = -15
(-15 + 7)2 = -15 - 1
(-8)2 = -16
-16 = -16
AC = √(40²-12²) = √(1600-144) = √1456 = 4√91
tanA = 12/4√91 = 3/√91 = 3√91/91
option а.
