let's bear in mind that, the sum of all interior angles in a polygon is
180(n - 2), n = number of sides in the polygon.
now, this is a PENTAgon, it has 5 sides, thus n = 5, so the sum of all interior angles is then, 180( 5 - 2) => 180(3) => 540°.
now let's add them up then.
[tex]\bf 4x+71+68+70+70=540\implies 4x+279=540\implies \blacktriangleright 4x=261 \blacktriangleleft\\\\\\x=\cfrac{261}{4}\implies \blacktriangleright x=65.25 \blacktriangleleft[/tex]
