The weight ratio of two bags of sugar, A and B, is 4:1. Take out 13 kg of sugar from bag A and put it into bag B. At this time, the weight ratio of the two bags of sugar is 7:5. Find the original weight of bag A?
甲、乙两袋糖的重量比是4：1，从甲袋中取出13千克糖放入乙袋中，这时两袋糖的重量比是7：5，求甲袋糖原来有多重？
<gadget id="calculator">5 / 12</gadget>
<output>5/12 = around 0.416667</output>

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

<gadget id="calculator">(5/12) - (1/5)</gadget>
<output>13/60 = around 0.216667</output>

<gadget id="calculator">13 / (13/60)</gadget>
<output>60</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">60 * (4/5)</gadget>
<output>48</output>

<result>48</result>