PLEASE HELP ASAP simplify 2x -7y=9

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

How do you write y-10=2 (x-8) in standard form

Which property was used to simplify the expression? 3c+9 +4c=3c+4c+9