It costs 18 yuan to buy 3 kilograms of pears and 4 kilograms of apples, and 27 yuan to buy 6 kilograms of pears and 5 kilograms of apples. How much is it to buy 1 kilogram of pears?
买3千克梨和4千克苹果共需18元，买6千克梨和5千克苹果共需27元，那么买1千克梨需多少元．
<gadget id="calculator">27 * 4</gadget>
<output>108</output>

<gadget id="calculator">18 * 5</gadget>
<output>90</output>

<gadget id="calculator">108 - 90</gadget>
<output>18</output>

<gadget id="calculator">6 * 4</gadget>
<output>24</output>

<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<gadget id="calculator">24 - 15</gadget>
<output>9</output>

<gadget id="calculator">18 / 9</gadget>
<output>2</output>

<result>2</result>