The best way to find the slope of lines is to use the slope formula, it makes life a whole lot easier, trust me. The formula is written as so:
So take two points from the line you need to formula for and plug it in
Line G slope using coordinates (0,1) & (1,3): slope= 2
Line F slope using coordinates (1,1) & (2,2): slope= 1
Line E slope using coordinates (1,0) & (3,1): slope= 0.5
Hope this helps :D