hi please help with the questions i am not understanding them at all thank you so so much

12. The average height of female children from birth to age 16. The equation f (t) = -115(0.85) + 165, where h is the height in cm and t is the age in years. [3 Marks Each] a) Find the average rate of change from age 1 to 4. b) Using the estimation of h = 0.01, find the instantaneous rate of change at age 7. 14. Determine the constraints a and b such that f(x) is continuous for all values of x. ax - b x-1 f (x ) = x - 2 -3x, 1