The mass of 1 cow is equal to the mass of 4 sheep, and the mass of 2 sheep is equal to the mass of 13 rabbits. The mass of 1 cow is equal to the mass of rabbits.
1头牛的质量等于4只羊的质量，2只羊的质量等于13只兔子的质量．1头牛的质量等于多少只兔子的质量．
<gadget id="calculator">13 * 2</gadget>
<output>26</output>

<result>26</result>