A certain type of tile costs $50 per square meter.

If the actual tiles are square tiles with sides 20 cm,
How much does one tile cost?

20cm * 20cm * $50/m^2 * m^2/(100cm)^2

= 20*20*50/100*100 = $2 per tile

makes sense, since 20cm = 1/5 m, so there are 25 tiles/m^2