<mp-units/framework/quantity.h>
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);