The perimeter of triangle is the sum of the three sides of the triangle.
x + 3x - 1 + 4x + 2 = 81
8x + 1 = 81
8x = 80
x = 10
The length of the sides of the triangle are 10 inches, 3(10) - 1 = 29 inches, 4(10) + 2 = 42 inches.
If you need help the answer is 14 use long division or just subtract all depending on what the numbers are.