mp_units::operator‐

template<
    std::derived_from<quantity> Q,
    auto R2,
    typename Rep2>
requires detail::CommonlyInvocableQuantities<std::minus<>, quantity, quantity<R2, Rep2>>
[[nodiscard]]
constexpr
Quantity auto
operator‐(
    Q const& lhs,
    quantity<R2, Rep2> const& rhs);