PQRS is a cyclic quadrilateral. If $$\angle$$P is four times $$\angle$$R and $$\angle$$S is three times $$\angle$$Q, then the sum of $$\angle$$Q and $$\angle$$R is:
As PQRS is a cyclic quadrilateral , and in a cyclic quadrilateral sum of tow opposite angles is 180 degree,
so ,angle P + angle R = 180 degree--------(1)Â and angle S +angle Q = 180 degree------(2)
It is given that angle P is 4 times angle R ( P= 4 R)--------(3)
also, angle S is 3 times angle Q (S=3 Q)--------(4)
so, from (1) and (3) P +R = 180Â
               P+ 4R= 180
               5R= 180
               R= 180/5=36 degree.
  from (2) and (4) S + Q= 180
             3Q + Q=180
              4Q=180
             Q=180/4= 45 degree.
So, Q+ R = 36 + 45 = 81 degrees.
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