Question 707072
This is the same as a line with ordered pairs, (k,C) and two points are given; find the equation for the line.  You are looking for C=mk+b, much like you were finding y=mx+b.  


The points on this line are (1.4,40), and (1.8,50).
Slope, m=(50-40)/(1.8-1.4)=25.
From C=mk+b, b=C-mk.  Pick a point and find b.

b=50-25*1.8=5


Equation would then seem, C=25k+5. 


If k=1.7, C cooking time predicted is C=25*1.7+5=47.5 minutes