Since NS bisects QNR, the angles SNQ and SNR will be congruent.
They are congruent that means they are equal to each other. We will set them equal to each other and find the value of x first.
6x - 57 = 2x + 15
6x = 2x + 72
4x = 72
x = 18
Now we will substitute 18 for x in each angle measure and find measure of them.
Angle SNQ = 6(18) - 57 = 51
Angle SNR = 2(18) + 15 = 51
Now we will add both angles to find the total measure of angle QNR.
51 + 51 = QNR
102 = QNR
Hope this helps :)