Question

(1.2,5.1) and has an x-intercept of 3.7

Answer 1

y=mx+a is the standard linear form. 0=3.7m+a so a=-3.7m
Another point on the line is (3.7,0) by definition of x-intercept.
The slope m=(5.1-0)/(1.2-3.7)=-5.1/2.5=-2.04.
The equation is y=-2.04x+3.7×2.04=-2.04x+7.548.