NP =PS, meaning they have the same length. so the perimeter is 3.5 + 4 + another 3.5.
For the area imagine you cut the triangle in half. from P to the middle of NS. Put the 2 triangle halves together to form a rectangle. (PS is now touching NP). This would be a 2x 3.5 rectangle. 2x 3.5 is 7, meaning both this imagined rectangle and the triangle have an area of 7cm^2.