Explanation:
In triangle DPQR, since PQ = QR = PR, it is an equilateral triangle, which implies that all angles are equal. If the measure of angle R (m R) is given by the expression (5x + 31)° and each angle in an equilateral triangle is 60°, we can set up the equation 5x + 31 = 60 to find the value of x.
To solve for x, follow these steps: