foo.cpp: In function 'int main()':
foo.cpp:134:16: error: no match for 'operator+=' (operand types are 'Fraction' and 'Fraction')
   fractions[i] += Fraction(0, 1, i + 1);
                ^
foo.cpp:134:16: note: candidate is:
foo.cpp:62:13: note: Fraction& Fraction::operator+=(Fraction&)
  Fraction & operator += (Fraction & n) {
             ^
foo.cpp:62:13: note:   no known conversion for argument 1 from 'Fraction' to 'Fraction&'