If slope of line 1 is -1/2 and is parallel to line 2 what's the slope of line 2

For two lines to be parallel, the lines have to have equal slopes. Line 2 should have the same exact slope as line 1.
if it was perpendicular then the line would have the reciprocal (for example: Line one has the slope of 3, then line two would have the slope of 1/3; get it?)