Find the largest angle of quadrilateral ABCD in degrees, if (angle A)/2 = (angle B)/3 = (angle R)/4.
We want the angles to form an arithmetic progression, so they are 36, 72, 108 144 degrees. The largest angle is then 144 degrees.
Find the largest angle of quadrilateral ABCD in degrees, if (angle A)/2 = (angle B)/3 = (angle R)/4. ( R is C )
(Angle A)/2 => 48 / 2 = 24
(Angle B)/3 => 72 / 3 = 24
(Angle C)/4 => 96 / 4 = 24
The largest angle D = 360 - 48 - 72 - 96 = 144º 
So basically I accidentally rigged the odds against you and the question was missing one critical piece of information.
The quadrilateral is cyclic. Which means you can inscribe it in a circle.
See if you can solve it again.
Actually I'm too lazy to wait so basically the opposite angles of a cyclic quadrilateral are supplementary, so angle A plus angle C is equal to 180. And, A plus C is 6 of those "units," so the missing angles must be 3 of them. So, since C has 4 of them, that is the largest angle. Since we have split up the quadrilateral into 12 of those units, each is 30 degrees. Therefore, 30*4=120.
Sorry
Big apologies
But in the end, we're both anonymous so no one actually cares.
