Hint: Perimeter is the distance around the particular object or shape. Given figure is in the shape of a triangle. So the perimeter can be found by adding sides.
Perimeter of the given triangle will be equal to the sum of lengths of its sides.
$\therefore $Perimeter of the given triangle = 30 + 35 + 55 = 120 cm
Perimeter is a path that surrounds an area (two dimensional shape). It can be the length of the outline of a shape. The perimeter of a circle or ellipse is called its circumference.