What is the measure of ∠adc in quadrilateral abcd? °

Based on what i know about mean, this doesn't add up.

Consider a cube that has sides of length l. now consider putting the largest sphere you can inside this cube without any point on the sphere lying outside of the cube. the volume ratio -volume of the sphere/ volume of the cube is 1. 5.2 × 10−1 2. 3.8 × 10−1 3. 1.9 4. 2.5 × 10−1 5. 3.8

Which of the following disjunctions is true? 4 + 4 = 16 or 6 - 5 = 11 4 · 3 = 7 or 3 - 2 = 5 8 - 5 = 13 or 7 · 2 = 12 7 - 4 = 11 or 6 + 3 = 9