Let
A(4,5) B(8,7) C(12,9) D(16,11)
1) Find the slope AB
m=(y2-y1)/(x2-x1)
m=(7-5)/(8-4)=0.5
2) Find the slope BC
m=(9-7)/(12-8)=0.5
3) Find the slope CD
m=(11-9)/(16-12)=0.5
The points represent a linear function
so
Find the equation of the line with m=0.5 and the point A(4,5)
we know that
y-y1=m*(x-x1)
y-5=0.5*(x-4)
y=0.5*x-2+5
y=0.5*x+3
therefore
the answer is
The equation is equal to y=0.5*x+3
