Assuming the figure is a parallelogram,
Also,
But 115 = (6x+11) + (4x+6)
115 = 6x - 11 + 4x + 6
115 = 6x + 4x - 11 + 6
115 = 10x - 5
10x = 115 + 5
10x = 120
x = 120/10
x = 12