Hello,
When you have an inscribed quadrilateral, the opposite sides are supplementary.
So you can write and solve the following equation.
x + 6x + 19 = 180
7x + 19 = 180
7x = 161
x = 23
Now, plug in 23 for X and we will find the measurement of B.
6(23) + 19
138 + 19
157
The measure of angle B is 157 degrees. (The picture is not drawn to scale)
Good luck,
MrEQ