Put a batch of apples in two baskets A and B at a ratio of 7:3. If 20 kilograms of apples are taken from A basket and put into B basket, then the apples in B basket account for 50% of the batch of apples. How many kilograms of apples are in the original basket?
把一批苹果按7：3的比装在甲乙两个筐里，如果从甲筐取出20千克苹果放入乙筐，那么乙筐中的苹果占这批苹果的50%．甲筐中原有苹果多少千克？
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">7 + 3</gadget>
<output>10</output>

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

<gadget id="calculator">(1/2) - (3/10)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">20 / (1/5)</gadget>
<output>100</output>

<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">100 * (7/10)</gadget>
<output>70</output>

<result>70</result>