Step 1: Use the given averages
Average of Anwar, Amit, Gopal = 45
⇒A+M+G=45×3=135
Average of Anwar and Amit = 43
⇒A+M=43×2=86
Average of Amit and Gopal = 42
⇒M+G=42×2=84
Step 2: Find Amit’s weight
Add equations (2) and (3):
(A+M)+(M+G)=86+84
A+2M+G=170
But from step 1:
A+M+G=135
Subtract:
(A+2M+G)−(A+M+G)=170−135
M=35
Amit’s weight = 35 kg