Question 262971
 city A population =68000
 amount of decrease =68000-80X 
  city B population=42000
 Amount of increase=42000+120x


 if both cities will have same population then
     68000-80x=42000+120x

      68000-42000=120x+80x
       26000 = 200x
        x= 26000/200
           130 

in 130 years both cities will have same population
check:  city A population=68000-80* 130
                           68000-10400
                            57600
        city B population = 42000+ 120*130
                            42000+15600
                            57600