A kind of fresh mushroom will lose 80% of its original mass after drying. There are 30 kilograms of dried mushrooms. How many kilograms of fresh mushrooms are dried? what is the formula
一种鲜蘑菇经晒干后将会失去原来质量的80%，现有干蘑菇30千克，它是由多少千克鲜蘑菇晒干而成的？算式是多少
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">30 / (1/5)</gadget>
<output>150</output>

<result>150</result>