Mathematics
posted by Anonymous .
There are 250 marbles altogether. Johan has 20 more than Mary who has 50 less than John. How many marbles does John have?

mary = x
johan = x+20
John = x+50
3 x + 70 = 250
3 x = 180
x = 60 = Mary
x+20 = 70 = johan
x+50 = 110 = John