Respuesta :

gmany
The formula of the midpoint of QR:
[tex]\left(\dfrac{x_Q+x_R}{2};\ \dfrac{y_Q+y_R}{2}\right)[/tex]

We have Q(2a; 0) and R(2b; 2c). Substitute:
[tex]\left(\dfrac{2a+2b}{2};\ \dfrac{0+2c}{2}\right)=(a+b;\ c)[/tex]