There used to be some rice and flour in the cafeteria. The mass ratio of flour to rice was 4:5. Later, 220 kilograms of flour were shipped in. At this time, rice accounted for 6/7 of the flour. How many kilograms of flour were there?
食堂原来有一些大米和面粉，面粉和大米的质量比为4：5，后来又运来220千克面粉，这时大米占面粉的(6/7)，原来有面粉多少千克？
<gadget id="calculator">7 / 6</gadget>
<output>7/6 = around 1.166667</output>

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

<gadget id="calculator">(7/6) - (4/5)</gadget>
<output>11/30 = around 0.366667</output>

<gadget id="calculator">220 / (11/30)</gadget>
<output>600</output>

<gadget id="calculator">600 * (4/5)</gadget>
<output>480</output>

<result>480</result>