Answer:
mS = 68 (B)
Explanation:
First, we are given mR, which is 56.
Next, we can figure out mQ by subtracting 124 from 180 (because it's a straight line) :: 180 - 124 = 56, SO, mQ = 56
Now, we know that the sum of all the interior angles is 180, so we'll subtract mR and mQ from that....
180 - (mR + mQ) >> 180 - (56 + 56) >> 180 - 112 = 68
therefore, mS = 68