There are two kinds of fruits in the fruit shop, watermelon and apple. The weight of the watermelon is 5 kg more than 3 times that of the apple. After selling 20 kg at the same time, the weight of the watermelon is 5 kg more than 4 times that of the apple. How many kg of watermelon are there in the fruit shop?
水果店有西瓜和苹果两种水果，西瓜的重量比苹果的3倍多5千克，同时卖出20千克后，西瓜的重量比苹果的4倍多5千克，水果店里西瓜原来有多少千克．
<gadget id="calculator">4 * 20</gadget>
<output>80</output>

<gadget id="calculator">5 - 5 - 20</gadget>
<output>-20</output>

<gadget id="calculator">80 + (-20)</gadget>
<output>60</output>

<gadget id="calculator">4 - 3</gadget>
<output>1</output>

<gadget id="calculator">60 / 1</gadget>
<output>60</output>

<gadget id="calculator">60 * 3</gadget>
<output>180</output>

<gadget id="calculator">180 + 5</gadget>
<output>185</output>

<result>185</result>