Xiaogang has 180 white rabbits and black rabbits in total. The white rabbits belong to black rabbits (4/5). How many white rabbits does Xiaogang have?
小刚家养白兔和黑兔共180只，白兔是黑兔的(4/5)，小刚家养白兔多少只．
<gadget id="calculator">4 + 5</gadget>
<output>9</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">180 * (4/9)</gadget>
<output>80</output>

<result>80</result>