First pound costs = [tex] $\verb#$2.41#$ [/tex]
Next 6 pound costs = [tex] $\verb#$0.41#$ [/tex] * 6 = [tex] $\verb#$2.46#$ [/tex]
cost per additional pound is [tex] $\verb#$0.39#$ [/tex] after 7 pounds.
Let x be the weight of package in pounds
additional pound is (x-7)
Cost of package = cost of 1 pound + cost of 6 pounds + cost of additional pounds
Given cost of package = 7.99
Cost =[tex] 2.41 + 2.46 + 0.39 (x-7) [/tex]
[tex] 7.99 = 2.41 + 2.46 + 0.39 (x-7) [/tex]
[tex] 7.99 = 4.87 + 0.39 (x-7) [/tex]
Subtract 4.87 on both sides
[tex] 3.12 = 0.39x - 2.73 [/tex]
Add 2.73 on both sides
[tex] 5.85 = 0.39 x [/tex]
Divide by 0.39 on both sides
[tex] x = 15 [/tex]
The package weight 15 pounds