If the mass of 3 coconuts + the mass of 1 watermelon = the mass of 10 apples, and the mass of 4 apples = the mass of 2 coconuts, then how many apples weigh the same as 1 watermelon?
如果3个椰子的质量+1个西瓜的质量=10个苹果的质量，4个苹果的质量=2个椰子的质量，那么多少个苹果的质量和1个西瓜一样重．
<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">10 - 6</gadget>
<output>4</output>

<result>4</result>