Sangita has already flown for a total of 50 hours + 9 hours + 121 hours = <<50+9+121=180>>180 hours
The flight time she has remaining is 1500 hours - 180 hours = <<1500-180=1320>>1320 hours
Sangita's monthly target must therefore be 1320 hours / 6 months = <<1320/6=220>>220 hours/month
#### 220