Answer:
F = 14i +17j
Explanation:
You want the endpoint F given that E = -2i +3j and the midpoint of EF is 6i +7j.
Midpoint
The midpoint M is the average of the endpoints:
M = (E+F)/2
End point
Solving for F, we find ...
2M = E+F
F = 2M -E = 2(6i +7j) -(-2i -3j)
F = 12i +2i +14j +3j
F = 14i +17j