The tax on a commodity is diminished by 30% but its consumption is increased by 15%. Find the decrease percent in the revenue derived from it?  Options.
A) 20 %
B) 18 %
C) 15 %
D) 12 %
E) 14 %

Rationale: "100 * 100 = 10000 70 * 115 = 8050 10000 - - - - - - - 1950 100 - - - - - - - ? = 20 % answer : a"
Answer: A