The price of raw materials has gone up by 15%, labour cost has also increased from 25% of the cost of raw material to 30% of the cost of raw material. By how much percentage should there be reduction in the usage of raw materials so as to keep the cost same?	Choose the most appropriate option:
A) 28% B) 17% C) 27% D) 24% E) Cannot determined
Solution: Let the initial cost of raw material be 100. So, initial labour cost was 25 and net cost was 125.   Now,   15% increment in raw materials cost and labour cost has gone up to 30% from 25 %.   Raw material cost = 115. And   Labour cost = (115 *30) = 34.5   So, New net cost,   = 115 + 34.5= 
<gadget id="calculator">115 + 34.5</gadget>
<output>149.5</output>
149.5   %reduction= 24.5/149.5 = 17%(approx.)   Answer: Option 17%
<result>B</result>
The price of raw materials has gone up by 15%, labour cost has also increased from 25% of the cost of raw material to 30% of the cost of raw material. By how much percentage should there be reduction in the usage of raw materials so as to keep the cost same?