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

March 31, 2021 | education

| Given the condition:

angle E = angle D + 19;

angle B = 0.3 * angle D.

By the theorem on the sum of the angles of a triangle:

angle B + angle D + angle E = 180 degrees;

0.3 * angle D + angle D + angle D + 19 = 180;

2.3 * angle D = 180 – 19;

2.3 * angle D = 161;

angle D = 161 / 2.3;

angle D = 70 degrees.

Then the angle B is equal to:

angle B = 0.3 * angle D = 0.3 * 70 = 21 (degree).

Answer: angle B = 21 degrees.

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