Alarge, triangular, orange symbol on the rear of a farm tractor is known as
o smv
mph
rpm
dmv.

It is known as SMV

Explanation:

The (SMV) emblem, a fluorescent orange triangle with retroreflective borders It warns approaching motorists to slow down. The SMV emblem is required by the Ohio Revised Code when moving "implements of husbandry" and farm machinery on public roadways.

Hope this helps  :  )

well if u read the book you would know that she meant to