Ive tryed a lot cant get right answer heres the diagram

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

In triangle △abc, ∠abc=90°, bh is an altitude. find the missing lengths. ah=4 and hc=1, find bh.

Aclassmate thinks that solving a system by graphing gives an exact answer when the lines appear to cross at a grid point, but only an approximate answer when they don't. explain why this isn't true.