I only need questions 2 and 3 it’s urgent could someone please help?

Which number line correctly shows 0.8 + 0.3?

Which equation can be used to measure the density of water in a spherical water tank? let w represent the number of water particles within the region.

If you were constructing a triangular frame, and you had wood in the length of 4inches, 4 inches, and 7 inches, would it make a triangle? would you be able to create a frame from these pieces of wood? yes or no. explain your mathematical thinking