# The degree measure of the EBC angle is 50º, which is 40% of the ABC angle.

July 24, 2021 | education

| **The degree measure of the EBC angle is 50º, which is 40% of the ABC angle. The angle DEB is 30% less than the angle EBC. find the degree measure of the angle ABD.**

Let’s derive the formula for finding the angle ABD:

From the condition, angle ABC = ABE + DBE + DBC = ABE + EBC (1).

Angle ABD = ABE + DBE (2).

Find the angle ABE from the first equation:

ABE = ABC – EBC.

Substitute this value into equation (2):

ABD = ABE + DBE = ABC – EBC + DBE.

Find the angle ABC and DBE from the conditions.

EBC = 0.4 * ABC.

Therefore, ABC = EBC / 0.4 = 50º / 0.4 = 125º.

The DBE is 100 – 30 = 70% of the EBC.

That is DBE = 0.7 * EBC = 0.7 * 50º = 35º.

Thus, the angle ABD = 125º – 50º + 35º = 110º.

Answer: the angle ABD is 110º.