Riya is applying to her garden. she applies it at a rate of 25 ,000 cm^3 of mulch for every m^2 of garden space. at what rate is ray applying mulch in m^3/m^2

The rate in m³/m² is 40m³/m².

1 m³ is literally a cube with sides that are 1 m in length.  1 m = 100 cm, so each side of this cube is 100cm in length.  Finding the volume means multiplying length by width by height:
100(100)(100)=1,000,000 cm³ in 1m³.

We know that we have 25,000cm³ of mulch; we divide to find how many cubic meters this is:
1,000,000/25,000 = 40 m³.

This makes the rate 40m³/m².