Question

What's the answer to this

Answer 1

Step-by-step explanation:

the angle CDB is the supplementary angle to 9x+10 (angle ADC).

that means they stand together for 180°. as all angles around a single point on one side of a line are together always 180°.

and then, the sum of all angles in a triangle is always 180°.

so,

CDB + (4x + 10) + 50 = 180

CDB = 180 - (9x + 10) = 180 - 9x - 19 = 170 - 9x

therefore,

(170 - 9x) + (4x + 10) + 50 = 180

170 - 9x + 4x + 10 + 50 = 180

-5x = -50

5x = 50

x = 10

angle CDB = 170 - 9x = 170 - 90 = 80°