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Determine the value of $x$.
Mathematics 0580 · IGCSE · Angles
Angles — practice question
A quadrilateral is shown in a diagram. Its interior angles are marked as $4x^{\circ}$, $(3x+75)^{\circ}$, $(87-x)^{\circ}$, and one right angle ($90^{\circ}$). The drawing is not to scale.