To determine if quadrilateral QRST is a parallelogram, we need to check if the consecutive angles sum to 180°. We know that angle Q measures 108°, and angle R measures \( 108 - 2x \). Therefore, the sum of angles Q and R is \( 108 + (108 - 2x) = 216 - 2x \). For QRST to be a parallelogram, we must have \( 216 - 2x = 180 \).
Solving for \( x \): \[ 216 - 2x = 180 \ 2x = 216 - 180 \ 2x = 36 \ x = 18 \]
Since we found a valid value for \( x \), quadrilateral QRST can be a parallelogram if angles Q and R sum appropriately. Thus, \( x = 18 \) indicates it is a parallelogram, assuming the properties of opposite angles and sides are satisfied.