Drag an answer to each box to complete this paragraph proof. given: triangle pqr with m∠p=(x)° , m∠q=(3x)° , and m∠r=(5x)° . prove: x = 20 by the triangle sum theorem, the sum of the angles in a triangle is equal to 180°. therefore using the given and triangle sum theorem, m∠p+m∠q+m∠r=180° . using the substitution property,