Can someone just give the answers please

Determine whether the set of whole numbers is closed under addition. explain why the set is or is not closed. give an example.

The lengths of two sides of a right triangle are given. find the length of the third side. round to the nearest tenth if necessary. a) y = 12/5x + 39/5 b) y = 5/12x + 5/39 c) y = 12/5x - 39/5 d) y = 5/12x - 5/39

Write the point-slope form of the line passing through (2, -12) and parallel to y=3x.