Answer
$W = 700J$
Work Step by Step
Since the gas is an ideal gas, the work done for isothermal process in path $1 \rightarrow 2$ is just the same as the heat, Q during that path according to the 'first law of thermodynamics'.
$\Delta U = 0 = W - Q$ so $ Q = W$
$W = (350K)(8J/K - 6 J/K) $
$W= (350K)(2.0J/K)$
$W = 700J$
