-45 + s = -105

To solve for "s", we can isolate "s" on one side of the equation by performing the same operation to both sides.

To isolate "s", we need to get rid of the -45 on the left side of the equation. We can do this by adding 45 to both sides:

-45 + 45 + s = -105 + 45

This simplifies to:

s = -60