Write a function in the form y=mx+b for the line that contains the point (-8.3, -5.2) and (6.4, 9.5)

A linear function has the form y=mx+b
using the points (-8.3, -5.2), (6.4, 9.5) and the elimination method: inserting x and y into the basic form results in
I:-5.2=-8.3m+b
II:9.5=6.4m+b
subtraction of II from I:
-5.2-9.5=-8.3m+b-6.4m-b
-14.7=-14.7m
-1=-m
-> m=1
insert this in II again:
9.5=6.4*1+b
9.5-6.4=b
3.1=b
-> y=x+3.1