#### Answer

(a) 7920 + 5280 + 7920 + 1320 + 2640 + 1320 + 2640 + (5280 - 1320*2) = 31680
(b) 95,040 feet
(c) 18 miles

#### Work Step by Step

(a) The distance around the combined parcels is found by adding up every side. The side missing the number can be found by subtracting 5280 - 320 - 320.
(b) The distance in feet around the parcels is 7920 + 5280 + 7920 + 1320 + 2640 + 1320 + 2640 + (5280 - 1320*2) = 7920 + 5280 + 7920 + 1320 + 2640 + 1320 + 2640 +(5280 - 2640) = 7920 + 5280 + 7920 + 1320 + 2640 + 1320 + 2640 + 2640 = 31,680 feet. For a three-strand barbed wire, we multiply 31,680 * 3 = 95,040 feet.
(c) Since there are 5280 feet in one mile, we convert 95,040 feet by dividing by 95,040 / 5,280 = 18.