The angle of deviation for a prism the is given by
$$
\Delta=(n-1) \times A
$$
Where,
\(n=\) refractive index of prism
\(A=\) angle of prism
Given: The two prisms when combined produce dispersion without deviation.
Conclusion: For no deviation for the two prism the deviation caused by two prism should be opposite to each other
$$
\begin{aligned}
&\left(n_{1}-1\right) \times A_{1}=\left(n_{2}-1\right) \times A_{2} \\
&A_{2}=\frac{\left(n_{1}-1\right) \times 4}{n_{2}-1} \\
&A_{2}=\frac{(1.54-1) \times 4}{(1.92-1)} \\
&A_{2}=2.3^{\circ}
\end{aligned}
$$
