well all these are FRACTIONS which means when u add them up they'll always be equal to ( 1 )
so for CAROL u'll have to add up ANN's and BRIANs fraction and subtract IT from 1....
in the other part u'll have to equate the amoun paid by ann and brian....
it might go go like this.......... let the price paid (= x)
ANN pays 2/5 of x = 2/5x
BRIAN pays 1/3 of x = 1/3x
so the equation will be -----------> BRIANs cost + 1600 = ANNs cost
> 1/3x + 1600 = 2/5x