There are apples, pears, oranges and peaches in a box each. It is known that the total weight of apples and pears is 55 kg; the total weight of pears and oranges is 45 kg; the total weight of oranges and peaches is 35 kg; and peaches are 5 kg less than apples. How many kilograms does the peach weigh?
有苹果、梨、橘子和桃各一箱．已知苹果和梨共重55千克；梨和橘子共重45千克；橘子和桃共重35千克；而且桃比苹果少5千克．桃重多少千克．
<gadget id="calculator">35 + 5</gadget>
<output>40</output>

<gadget id="calculator">55 - 45</gadget>
<output>10</output>

<gadget id="calculator">40 - 10</gadget>
<output>30</output>

<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">35 - 15</gadget>
<output>20</output>

<result>20</result>