A tank of water, use (1/2) and 5 buckets, and there is 30% left, how many buckets are there in this tank of water?
一缸水，用去(1/2)和5桶，还剩30%，这缸水有多少桶？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(1/2) + (3/10)</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">5 / (1/5)</gadget>
<output>25</output>

<result>25</result>