p = a + b + c
a = longest side
b = middle
c = shortest
p = 3077
c = b - 71
a = b + 376
(b + 376) + b + (b - 71) = 3077
3b + 305 = 3077
3b = 3077 - 305
3b = 2772
b = 2772/3
b = 924 <== middle side is 924 miles
c = b - 71
c = 924 - 71
c = 853 <== shortest side is 853 miles
a = b + 376
a = 924 + 376
a = 1300....<== longest side is 1300 miles