First. There are 12 tons of chemical fertilizers in two warehouses. If 20% of warehouse A is moved into warehouse B, so that the ratio of fertilizer tons in warehouse A and warehouse B is 1:2, how many tons of fertilizer does warehouse A have?
甲．乙两个仓库共存化肥12吨．如果把甲仓库的20%搬入乙仓库，这样甲、乙仓库化肥吨数之比是1：2，甲仓库原有化肥多少吨？
<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(1/3) / (4/5)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">12 * (5/12)</gadget>
<output>5</output>

<result>5</result>