X 0 and x 6.
The average rate of change of the function between x 0 and x 6.

13/115

Step-by-step explanation:

The average rate of change is given by:

[f(b)-f(a)]/[b-a]

Given that:

f(x)=(2x-1)/(3x+5)

thus

ARC=[f(6)-f(0)]/[6-0]

f(6)=(2*6-1)/(3*6+5)=(12-1)/(18+5)=11/23

f(0)=(2*0-1)/(3*0+5)=(0-1)/(0+5)=-1/5

thus

ARC=(11/23-(-1/5))/(6-0)=(11/23+1/5)/6=(78/115)/6=13/115

x= cost per bracelet

number of bracelets * x + shipping charge = total cost

so

9x+9=72