Answer
$49.056 g NaHSO_3$
Work Step by Step
We can find the mass of $NaHSO_3$ as
$25.0 g\space NaCO_3\times \frac{1 mol \space Na_2CO_3}{106.0g \space Na_2CO_3}\times \frac{2 mol\space NaHSO_3}{1 mol \space Na_2CO_3}\times\frac{104.0g \space NaHSO_3}{1 mol\space NaHSO_3}=49.056 g NaHSO_3$
