Answer: m = -1
Explanation:
Because it is indicated that the equation is a line, it will be linear so we can use the equation: y = mx + b. m is the slope and b is the y-intercept.
8 = 1m + b <- substitute (1,8) into the equation y = mx + b
12 = -3m + b <- substitute (-3,12) into the equation y = mx + b
Solve the system of equations by elimination.
8-12 = -4; 1--3m = 4m; b-b=0
-4 = 4m + 0
m = -1