Vector AB can be calculated:
AB = <bx-ax , by-ay>
AB= <-5-4 , 1-3>
AB= <-9 , -2>
AC = -2*AB
AC = -2 *<-9 , -2>
AC = <18 , 4>
Now we can calculate coordinates of point C:
AC = <cx-ax , cy-ay>
<18 , 4> = <cx-4 , cy-3>
18=cx-4
cx=22
4=cy-3
cy=7
Coordinates of the terminal point C (22,7).
