Question

the sides of a triangle are 2x+3y, x+5y and 7x-2y.find its perimeter.

Answer 1

perimeter of triangle is = sum of all sides
                                 = (2x+3y) + (x+5y) + (7x-2y)
                                 = 10x+6y

Answer 2

perimeter of triangle = sum of the 3 lengths of 3 sides  i.e.,
                             = 2x+3y+x+5y+7x-2y
                             = 2x+x+7x+3y+5y-2y
                             = 10x+6y