Math.. how to get linear function
posted by Jack .
The total length y is a linear function of the tail length x with great accuracy. The domain is the interval from 30mm to 200mm, and the range is the interval from 200mm to 1400 mm. The following two points are given: X0= 60mm, Y0= 455mm, X1=140mm, Y1= 1050mm. Find the equation of y as function of x. The answer (equation) is y=7.44x+9 but how do I get that???

Y=mx +b
yo=m*xo+b
455=60m+b
y=m*x1 + b
1050=m*140+b
You have two equations. Subtract the first from the second.
(1050455)=m(14060)+b(11)
solve for m,
then, put that m in either of the equations, and solve for b.