The rate of increase is defined by the slope.
As all the equations of the lines are in slope-intercept form, the slope is the coefficient of x.
Then, we can order in increasing value of their slopes.
The least increasing line is:
1) y=-1/2*x+1/2
Then, in increasing order, we have:
2) y=1/2*x-2
3) y=3/4*x-10
4) y=4/3*x-7/3
5) y=3/2*x-11/2
6) y=5/2*x+10