Draw a set of objects where you can find a fractional part of the group using the total number of objects by using subgroups

Draw 20 equilateral triangles such that 5 triangles having sides measure 4 cm , 7 triangles have sides measure 7 cm , 3 triangles have side 10 cm and rest of the triangles have side of measure 5 cm.

This will become a set of equilateral triangles .

Let consider a subgroup set of the original set of having equilateral triangle with side-length of 5 cm.

Then the number of triangle having side-length 5 cm= 20-5-7-3=5

Now, the fraction of the group having triangle with side- length 5 cm is given  by:-