For a rhombus, opposite sides are parallel, and opposite angles are equal. And the diagonals "p" and "q" of a rhombus bisect each other at right angles. A quadrilateral has a sum of internal angles which is 360 degrees. Two of the angles in the given rhombus is equal to 2x42 = 84. Therefore, the angle ABC would be (360 - 84 - 84 ) / 2 = 98 degrees.
