The school breeding group raises 180 gray rabbits, 20 less than 4 times the number of white rabbits. How many white rabbits does the breeding group have? (equation)
学校饲养小组养灰兔180只，比白兔的4倍少20只，饲养小组养白兔有多少只？(方程)
<gadget id="calculator">180 + 20</gadget>
<output>200</output>

<gadget id="calculator">200 / 4</gadget>
<output>50</output>

<result>50</result>