hi im in grade 8 and i need help with a question. A sloped mountain road is 12.7 km long. it covers a horizontal distance of 8.9m. What is the change in the elevation of the road?

I know the the formula and stuff but my teacher told me that since the units arent the same it will affect the pythagorean theorem.

so that confuses me. so can anybody help me figure this out.