To answer this question, we need to see the picture or description that goes along with it.
Complete Question
The complete question is shown on the first and second uploaded image
Answer:
The expression is
Explanation:
Generally smallest workdone done by a gas is mathematically represented as

Generally for an isothermal process

=> 
Generally the total workdone is mathematically represented as

=> 
=> ![nRT [lnV] | \left \ {V_f}} \atop {V_o}} \right.](https://tex.z-dn.net/?f=nRT%20%5BlnV%5D%20%20%20%7C%20%5Cleft%20%5C%20%7BV_f%7D%7D%20%5Catop%20%7BV_o%7D%7D%20%5Cright.)
=> ![W_c = nRT [ln(V_f) - ln(V_o)]](https://tex.z-dn.net/?f=W_c%20%3D%20nRT%20%5Bln%28V_f%29%20-%20ln%28V_o%29%5D)
=> 
From the question 
=> 
at initial state