Don't mind the work below number 14 but i can't figure #14 out?

Find the midpoint m of z1=(8+5i) and z2=(12+3i)

Solve each quadratic equation by factoring and using the zero product property. 10x + 6 = -2x^2 -2

What is the missing statement in step 4? ? rts ? ? vtu and ? rtu ? ? vts ? rts ? ? rvs and ? rtu ? ? stv ? vrs ? ? vru and ? usr ? ? usv ? vur ? ? vus and ? uvs ? ? sru