Hello, you forgot to provide the graphs but anyway this problem can be solved without them. If you want a graph where y is increasing by 1/2 each time x increases by 1, then you want a general equation in the form of:
where c is any constant.
Assuming the value of 0 for c, notice that when x is 1, y is 1/2, and when x is 2, y is 1. Therefore 1/2 was increased for y upon increasing 1 for x.