$\begin{array}{l}\text{Here,\hspace{0.17em}}\\ \Rightarrow \text{160\% of 250 +? = 120\%of 400}\\ \\ \Rightarrow \text{\hspace{0.17em}? = 120\% of 400}-\text{160\% of 250}\\ \\ \Rightarrow \frac{\text{120}}{100}\times \text{400}-\frac{160}{100}\times 250\\ \\ \Rightarrow \text{120}\times \text{4}-\text{16}\times \text{25}\\ \\ \Rightarrow \text{ 480}-\text{400 = 80}\end{array}$

Hence, Option C is correct.