Question

see attachment.. please help guys :)

Answer 1

If there is a perpendicular bisector, that means it will divide the triangle into 2 smaller triangles of equal parameters. In this case, the sides will be equal to, so to find 'x' you just equate them:
3x + 4 = x + 12
3x - x = 12 - 4
2x = 8
x = 8/2 = 4
x = 4