Answer:
m=4, n=5
Step-by-step explanation:
given the midpoint of diagonals, the opposite sides of the midpoint of every diagonal are congruent, so
9 = 2n-1
m+8 = 3m
solving for n first:
9+1 = 2n-1+1
10 = 2n
n = 5
solving for m:
m+8-m = 3m-m
8 = 2m
m = 4
