Sumathi says that the area of a triangle PQR is, A=1/2×8×7 CM. rajini says that it is A=1/2×9×7 cm. who is correct? give reason?

please answer me fast!!!

In order for the function to be linear, what must m be and why? m = 22 because the rate of change is 1. m = 20 because the rate of change is 3. m = 22 because the rate of change is -1. m = 20 because the rate of change is -3.