The Total solution for NCERT class 6-12
∠AOB = 75o (given)
In a quadrilateralABCD, bisectors of angles A and B intersect at O, then
∠AOB = 1/2 (∠ADC + ∠ABC)
or ∠AOB = 1/2 (∠D + ∠C)
By substituting givenvalues, we get
75 o =1/2 (∠D + ∠C)
or ∠C + ∠D = 150 o