ERROR: Bind non-const lvalue reference of type to an rvalue of type

I have an error that I couldn't solve in my code.

If I call my function in main as the following :

Ratio f34(3L,4L);
const Ratio one(f34.divide(f34));

or

Ratio s = Ratio(7).divide(Ratio(8));

I have an error that says

   error: cannot
   bind non-const lvalue reference of type ‘Ratio&’ to an
   rvalue of type ‘Ratio’

and here is my Ratio constructor and divide function :

Ratio::Ratio( long numerator,  long denominator) : nu(numerator) , de(denominator) {
    if (denominator == 0) {
        throw std::runtime_error("Cannot divide by 0");
    }
}

Ratio Ratio::divide(Ratio r) {

        long num = r.de *nu;
        long den = de * r.nu;
        Ratio result(num,den);

        return result;

    }

Note : nu and de are private variables in Ratio class.

I tried to change divide argument to be ( const Ratio &r ), but that did not solve the problem. I still have the same error.

What I understand is that the compiler complained that he can not make a temporary copy of an object. I still have no idea how can I solve it. I tried every thing!! please help :).