The weight of a pig is equal to the weight of 4 sheep, and the weight of 1 sheep is equal to the weight of 9 rabbits. If a rabbit weighs 5 kg, how much does a pig weigh?
一头猪的重量等于4只羊的重量，1只羊的重量等于9只兔的重量，如果一只兔重5千克，那么一头猪重多少千克．
<gadget id="calculator">4 * 9 * 5</gadget>
<output>180</output>

<result>180</result>