let

x = the number of viewers of the final mash episode got

y = the number of viewers of the who killed jr episode of dallas got

the total number of viewers for these 2 shows was 91 million

x + y = 91

with mash getting 9 million more viewers

x = y + 9

by solving the system of equations

x + y = 91

x = y + 9

we find

x = 50 millions viewers

y = 41 million viewers

the final mash episode got 50 millions viewers.

the who killed jr episode of dallas got 41 millions of viewers.