Help me with part B and C appease <3 please help!!

Step-by-step explanation:

a.

y=0.75x

y-y1=(y2-y1)/(x2-x1)×(x-x1)

y-3=(6-3)/(8-4) (x-4)

y-3=3/4(x-4)

y-3=3/4 x-3

y=3/4 x-3+3

y=3/4 x

if y=f(x)

f(x)=0.75x

c.

f(12)=0.75×12=9$

a function could be identified in 3 ways either on a chart,graph, or ordered pairs. first a function is that each point has its own. the rule is that there can be many x's to one y but there can not be 2 x's at different y's. so on a graph when you put a straight line through the y's there should be one dot only to be a function.

step-by-step explanation:

it’s the first one your welcome