From the solution.BAC = 85 degrees.ABD = 20 degrees.ACD = x°,And the problem is growing, says BDC angle 4 times the angle ACD therefore have WA.BDC = 4x degrees.
The prosecution will have BAC = 85 ° ABD = 20 degrees to the ACD = x degrees and we were told that the BDC is four times that of the ACD, so that BDC = 4x degrees.