Section MoreUnitDivisor.
Variable R : idomainType.
Variable d : {poly R}.
Hypothesis ulcd : lead_coef d \in GRing.unit.
Implicit Types p q : {poly R}.

Lemma divp_pmul2r p q :
lead_coef p \in GRing.unit ->  q * d %/ (p * d) = q %/ p.