Question 1190073
p = perimeter.
p = f + f + 4 + f + 5
combine like terms to get p = 3f + 9
when p = 51, the formula becomes 51 = 3f + 9
subtract 9 from both sides of the equation to get 42 = 3f
divide both sides of the equation by 3 to get 14 = f.
the length of the 3 sides are 14, 14 + 4 = 18, 14 + 5 = 19
their sum is equal to 14 + 18 + 19 = 51.