Answer:
mid point formula is :
[tex]((\frac{x_{1}+x_{2} }{2} ),(\frac{y_{1}+y_{2} }{2} ))\\[/tex]
and B (-1,-5) is the mid point of AC.
Assuming that x2 and y2 are coordinates of C, so x2 = 4 and y2 = -1
[tex]\frac{x_{1}+x_{2} }{2} = -1\\\frac{x_{1}+4}{2} = -1\\ x_{1} + 4 = -2\\ x_{1} = -6[/tex]
and again,
[tex]\frac{y_{1}+y_{2} }{2} = -5\\y_{1} + (-1) = -10\\{y_{1} -1 = -10\\\\{y_{1} = -9[/tex]
coordinates of A (-6,-9)
