let
A-----> the point (0.25,1)
B-----> the point (0.50,1.75)
we know that
the equation that represents the linear function is the equation of a line
so
step 1
find the slope m with the points A and B
m=(y2-y1)/(x2-x1)-----> m=(1.75-1)/(0.50-0.25)---> m=0.75/0.25--> m=3
step 2
with m=3 and point A (0.25,1)
find the equation of a line
y-y1=m*(x-x1)-------> y-1=3*(x-0.25)----> y=3x-0.75+1----> y=3x+0.25
the answer is
y=3x+0.25
see the attached figure