To solve this problem, we have to remember the triangle sum theorem, that says that the sum of the interior angles of a triangle is 180°. To find x, sum the expressions for each angle and make it equal to 180, this way

With this value, find the measure of each angle.

Finally, let's remember this: the wider the angle, the longer is its opposite side. It means, the ordered sides from shortest to longest are:
AB (opposite to angle C)
BC (opposite to angle A)
AC (opposite to angle B)