At a certain fast food restaurant, Brian can buy 3 burgers, 7 shakes and one order of fries for Rs 120 exactly. At the same place, it would cost Rs 164.50 for 4 burgers, 10 shakes and one order of fries. How much would it cost for an ordinary meal of one burger, one shake and one fries? (a) Rs 21     (b) Rs 31    (c) Rs 41     (d) Cannot be determined