PLEASE HELP 7 grade question:(

The square pyramid has a volume of 441 cubic inches. what is the value of x? 1/7x is the height x is the base

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

Prove that the value of the expression 7^8–7^7+7^6 is divisible by 43.