12 buckets of water fill a tank when the capacity of each bucket is 49 litres. How many buckets will be needed to fill the same tank, if the capacity of each bucket is 7 litres?  Select:
A) 39
B) 84
C) 80
D) 82
E) 86

Rationale: capacity of the tank = ( 12 ã — 49 ) litre number of buckets required of capacity of each bucket is 17 litre = 12 ã — 49 / 7 = 12 ã — 7 = 84 answer is b
Answer: B