Attached the solution with work shown.
3 + 9 = 12/3 = positive 4 the missing number in the equation is 12/3.
52.9109 in pounds if that's what your asking.
Let x = the unknown number to get x = 6
Answer:
13) Is a linear function. The points form a straight line
14) Is an exponential function. The points form a curved line.