Question

William has a regular hexagon with sides that are 2 units each. How many equilateral triangles with 1- unit sides can be put together to make the hexagon?

Answer 1

In a regular hexagon, each side is contained in a separate equilateral triangle with side of 2-units.  That makes six equilateral triangles with side 2-units.
Further, each equilateral triangle of side 2-units contains four (4) equilateral triangles of side 1-unit.
Therefore the total number of equilateral triangles of side 1 units in a hexagon with side two units is 6*4=24.