C=20 I think the answer is that
Is there more to this problem? By saying f(4), you'd be inputting a 4 for every variable x. There is not enough info here to answer the question.
Y=mx+b where m=slope=(dy/dx) and b=y-intercept (value of y when x=0)
You have two points...(1,-2),(3,2) so
m=(y2-y1)/(x2-x1)=(2--2)/(3-1)
m=4/2=2 now that you have the slope...
y=2x+b, you can use either point to solve for the y-intercept, I'll use (3,2)
2=2(3)+b
2=6+b
b=-4 so the line is:
y=2x-4
D. Slightly acidic is 5.0 to 5.5
