Answer
See the detailed answer below.
Work Step by Step
We know that the emf is given by
$$\varepsilon=\varepsilon_0\cos\phi $$
where
$$\phi=\omega t=2\pi f t$$
$$\varepsilon=\varepsilon_0\cos(2\pi f t) $$
Plug the known;
$$\varepsilon=50\cos(2\pi \times 110 \times 3\times 10^{-3}) $$
$$\varepsilon= 50\cos119^\circ =\bf -24\;\rm V$$
See the graph below,
