Answer:
 final temperature is 300K
Step-by-step explanation:
Given data
temperature TH0 = 450 K 
temperature TC0 = 200 K
to find out 
final temperature
solution
we consider TH id temperature of hot and TC is temperature of cold object
so
dQH = -mc dTH ..........1
dQC = mc dTC ............2
and for max work 
dQH/ TH = dQC/TC
put 1 and 2 here 
 -mc dTH / TH = mc dTC/ TC
now integrate both side from 450 to T and 250 to T 
 = 
 
we get ln 450/T = ln T/200 
so Temp = √(450*200) 
Temp = 300K 
 final temperature is 300K