Exact values of complexity for an infinite number of 3-manifolds

We find the exact values of complexity for an infinite series of 3-manifolds. Namely, by calculating hyperbolic volumes, we show that $c(N_n)=2n$, where $c$ is the complexity of a 3-manifold and Nn is the total space of the punctured torus bundle over $S^1$ with monodromy $\begin{pmatrix}2&1\\1&1\end{pmatrix}n$. We also apply a recent result of Matveev and Pervova to show that $c(M_n)\ge 2Cn$ with $C\approx 0.598$, where a compact manifold $M_n$ is the total space of the torus bundle over $S^1$ with the same monodromy as $N_n$, and discuss an approach to the conjecture $c(M_n)=2n+5$ based on the equality $c(N_n)=2n$.