Respuesta :

Area of triangle is 435 sq cm.
  P = s1 + s2 + s3
70 = (4x+1) + (3x) + (3x-1)
70 = 4x + 1 + 3x + 3x - 1
70 = 10x
/10   /10
  7 = x

   3x = ?
3(7) = 21
(base)

   3x - 1 = ?
3(7) - 1 = ?
  21 - 1 = 20
  (height)

A = bh / 2
   = (21)(20) / 2
   = 420 / 2
   = 210

Therefore the area is 210cm².