Simplify the following text for a Grade 9 native English-speaking person.
Original: In 1990 Phelps took part in a mission from the then-forming EBRD to Moscow , where he and Kenneth Arrow designed a proposal for the reform of the USSR .
Simplified: In 1990 Phelps took part in a mission from the EBRD to Moscow , where he and Kenneth Arrow worked on the reform of the USSR .