15 9/10-3 1/5 reduced to lowest term

Brent wants to know what is 5 x 1/2

Rhombus adef is inscribed into a triangle abc so that they share angle a and the vertex e lies on the side bc . what is the length of the side of the rhombus if ab=c, and ac=b.

X^2/100+y^2/25=1 the length of the major axis is: a)5 b)10 c)20