I would like help with the steps necessary to do part c

39. The number N of US cellular phone subscribers (in millions) is shown in the table. (Midyear estimates are given.) 1998 2000 2004 1996 2002 2006 44 69 109 141 182 233 (a) Find the average rate of cell phone growth (i) from 2002 to 2006 (ii) from 2002 to 2004 (iii) from 2000 to 2002 In each case, include the units. (b) Estimate the instantaneous rate of growth in 2002 by taking the average of two average rates of change. What are its units? (c) Estimate the instantaneous rate of growth in 2002 by measuring the slope of a tangent