In circle O, RT and SU are diameters. Circle O is shown. Line segments S U and R T are diameters. Line segment O V is a radius. Point V is between points R and U. Angle W O R is (13 x) degrees and angle T O U is (15 x minus 8) degrees. If mArc R V = mArc V U , what is mArc V U ? 47° 52° 64° 87°