The tax on a commodity is diminished by 10% but its consumption is increased by 20%. Find the decrease percent in the revenue derived from it?  Select.
A) 18%
B) 4%
C) 32%
D) 12%
E) 52%
100 * 100= 
<gadget id="calculator">100 * 100</gadget>
<output>10_000</output>
10000   80 * 120= 
<gadget id="calculator">80 * 120</gadget>
<output>9_600</output>
9600   10000------- 400   100 ------- ?= 4%   Answer:4%
<result>B</result>
The tax on a commodity is diminished by 10% but its consumption is increased by 20%. Find the decrease percent in the revenue derived from it?