Answer:
average rate of change = 2
Explanation:
the average rate of change of k(x) in the closed interval [ a, b ] is

here [ a, b ] = [ 13, 17 ] , then
f(b) = f(17) = 2(17) + 15 = 34 + 15 = 49
f(a) = f(13) = 2(13) + 15 = 26 + 15 = 41 
average rate of change = 
 =
 = 
 = 2
 = 2