<mp-units/framework/quantity.h>
template<
std::derived_from<quantity> Q,
RepresentationOf<quantity_spec> Value>
requires detail::DimensionlessOne<Q::reference> &&
detail::InvokeResultOf<quantity_spec, std::minus<>, Rep, const Value&>
[[nodiscard]]
constexpr
Quantity auto
operator-(
Q const& lhs,
Value const& rhs);