a linear function is of the type y=a+b*x where a and b are constants and x and y are variables.if the function passes through points (2,4) and (1,4) one can substitue x with 2 and y with 4 to get an equation with two unknowns a and bnow we can substitute (x,y) with (1,4) to get a second equation with two unknowns a and bnow we have two equations with two unknowns a and bsolve this pair and you will get the equation of the first linethe slope is b.Similarly solve the coeficients of the other linesanother simpler approach would be b=(y2y1)/(x2x1) so in the first pair (x1,y1)=(2,4) the second pair (x2,y2) would be (1,4)b=(44)/(12)=(8)/(3)=(2+2/3)
