Step-by-step explanation:
I assume AB is supposed to be a straight line. yes ?
in that case please remember that all angles on top of a line (and then again below a line) must sum up to 180 degrees (this is what it takes to flip a "stick" on that line from left to right).
so, COD covers already 90 degrees of these 180.
that means AOD + BOC = 180 - 90 = 90 degrees.
now we know that the 2 angles are in the ratio of 1:5.
that means that BOC is 5 times as large as AOD.
and we can be more direct :
since the 2 angles are in the ratio 1:5 we are actually splitting the remaining 90 degrees into 6 parts (5+1).
and BOC gets then 5 of these 6 parts, and AOD gets the remaining 1 part.
so,
90/6 = 15
therefore, one of these parts is 15 degrees.
so, we know AOD = 15 degrees.
BOC = 5×15 = 75 degrees
or simply 90 - 15 = 75 degrees
