Answer:
B = (5, -1)
Explanation:
We can use the required relation to find an expression for B in terms of the given points.
AB = (1/3)(BC)
B -A = (1/3)(C -B)
B = (1/3)C -(1/3)B +A . . . . . add A
(4/3)B = (1/3)C +A . . . . . . . add 1/3B
B = (1/4)C +(3/4)A = (C +3A)/4 . . . . . . multiply by 3/4
B = ((2, -7) +3(6, 1))/4 = (20/4, -4/4) . . . . . substitute given values
B = (5, -1)