Rich is 9 years old. Ruth is 18 years old. Finally, Carla is 6 years old. Furthermore, Ri represent for Rich, Ru represent for Ruth and C represent for Carla. So:
Ri= 3+C
Ru= 2Ri
Ri+Ru+C=33
Ri+2Ri+Ri-3=33
4Ri-3=33
4Ri=36
Ri=9
Ru=9×2 or 18
C= 9-3 or 6.
Hope it help!
