Dongdong drinks a cup of 200ml pure milk, first drink (1/4), fill up with water, then drink (1/5), how many milliliters of pure milk is there in the cup at this time.
冬冬喝一杯200毫升的纯牛奶，先喝(1/4)，加满水后，又喝了(1/5)，这时杯中的纯牛奶还有多少毫升．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">200 * (1/4)</gadget>
<output>50</output>

<gadget id="calculator">200 - 50</gadget>
<output>150</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">200 - 50 - 30</gadget>
<output>120</output>

<result>120</result>