Let the weights of Gopal, Akshay, Athul be (G, A, T) respectively.
Average of Gopal, Akshay, Athul = 46 kg
3G+A+T=46⇒G+A+T=138(1)
Average of Gopal and Akshay = 40 kg
2G+A=40⇒G+A=80(2)
Average of Akshay and Athul = 45 kg
2A+T=45⇒A+T=90(3)
Add equations (2) and (3)
(G+A)+(A+T)=80+90
G+2A+T=170
Subtract equation (1)
(G+2A+T)−(G+A+T)=170−138
A = 32
Weight of Akshay = 32 kg