253-(x-459)=138
x-459=253-138
x-459=115
x=115+459
x=574
502-(217-x)=421
217-x=502-421
217-x=81
x=217-81
x=136
871-(x+157)=385
x+157=871-385
x+157=486
x=486-157
x=329
253-(x-459)=138
x-459=253-138
x-459=115
x=115+459
x=574
502-(217-x)=421
217-x=502-421
217-x=81
x=217-81
x=136
871-(x+157)=385
x+157=871-385
x+157=486
x=486-157
x=329