I'm not sure what your thoughts were here, so I don't know, whether this is the right way. There are more than one way to get the correct result. In ##\mathbb{Z}_6## there is neither an element ##6## nor ##7##; at least not in its usual representation. But you can use the normal way to solve such equations:
$$
x+5=1\,\vert \,-5 \\
x = 1 - 5 \,=\, -4
$$
and then determine what ##-4 \in \mathbb{Z}_6## is.