Question 24118
Let "x" represent the weight, in pounds, of any package.
Cost to send the package = cost of 1st pound + cost of additional pounds
Cost for x pounds = $15 + $3(x-1)
 C(x) = 15+3(x-1)
If x=7, C(7)=15+3(7-1)
        C(7)=15+3(6)
        C(7)=33   (The cost to send 7 lbs. is $33)

Cheers,
Stan H.