Answer:

Step-by-step explanation:
Recall that the formula for density is:

therefore for this case we have:

There are 360 degrees in the rhombus which means the equilateral triangles has 180 degrees (because it is half the rhombus and also it is the angle sum of a triangle). It is equilateral meaning all sides and angles are the same so they all must be 60 (180/3)
Now this must mean that angle a is equal to the opposing angle being 60
The answer is 8/7. 6/7 divided by 3/4 = 6/7 x 4/3. 6/7 x 4/3 = 24/21 = 8/7