Zhang Bin bought 3 catties of ducks and 4 catties of chickens and paid a total of 9 yuan and 6 cents. Li Jie bought 3 catties of chickens and 4 catties of ducks and paid 9 yuan and 3 cents. How much more per catty of chickens than per catty of ducks.
张彬买了3斤鸭和4斤鸡，共付出9元6角，李杰买了3斤鸡和4斤鸭，付出9元3角，每斤鸡比每斤鸭多多少元．
<gadget id="calculator">2.7 * 3</gadget>
<output>8.1</output>

<gadget id="calculator">9.6 - 8.1</gadget>
<output>1.5</output>

<gadget id="calculator">9.3 - 8.1</gadget>
<output>1.2</output>

<gadget id="calculator">1.5 - 1.2</gadget>
<output>0.3</output>

<result>0.3</result>