In triangle BDE, angle B is 30 angle D, and angle E is 19 greater than angle D. Find angle B.

By condition, △ BDE is given: ∠B = 0.3 * ∠D, ∠E = ∠D + 19 °.
By the theorem on the sum of the angles of a triangle, the sum of all interior angles of any triangle is 180 °, then:
∠B + ∠D + ∠E = 180 °.
Let ∠D = x, then ∠B = 0.3 * x, ∠E = x + 19 °. Substitute these values into the expression for the sum of the angles of the triangle:
0.3 * x + x + x + 19 ° = 180 °.
Let’s solve the resulting linear equation with one variable:
2.3 * x = 180 ° – 19 °;
2.3 * x = 161 °;
x = 161 ° / 2.3;
x = 70 °.
Thus, ∠D = 70 °.
Find the degree measure ∠B:
∠B = 0.3 * ∠D = 0.3 * 70 ° = 21 °.
Answer: ∠B = 21 °.