From Mechanics

Here we use

\displaystyle \mathbf{r}=\mathbf{u}t+\frac{1}{2}\mathbf{a}{{t}^{\ 2}}+{{\mathbf{r}}_{0}}

According to the text

\displaystyle \mathbf{u}=\mathbf{i}+2\mathbf{j}

We assume the starting point is the origin so that \displaystyle {{\mathbf{r}}_{0}}=0.

At \displaystyle t=10+40=50 we obtain

The distance is the magnitude of this vector