so y=mx+b
cost=m(number of pages)+b
cost=y
# of pages=x
so points are
(x,y)
(50,1.55)
(100,2.25)
(150,2.95)
(20,3.65)
so solve for slope/m you do (y₁-y₂)/(x₁-x₂) so
just use any for example
(1.55-2.25)/(50-100)=-0.70/-50=1 times 0.7/50=7/500= (to convet to decimal form) 14/1000=1.4/100=0.14/10=0.014/1=0.014
slpoe is 0.014
y=0.014x+b
input one of the points exg 50 for x and 1.55 for y and solve for b
1.55=0.014(50)+b
1.55=.7+b
subtract .7 from both sides
0.85=b
so the equation is
y=0.014x+0.85
which is C
