A lattice point is a point with integer coordinates. How many lattice points $(x,y)$ with $-100\le x\le 100$ and $-100\le y\le 100$ are on the graph of the parametric equations

Question

\begin{align*}
x&=30-40\cos t,\\
y&=-50 + 30\cos t?
\end{align*}

Answer 1

21