Two transport teams, A and B, want to transport a batch of relief materials to the earthquake-stricken area. Team A can transport 64.4 tons per day, which is 75% more than that of team B; When 1/2 of the material is used, it transports 138 tons more than team B. How many tons are there in total for this batch of relief supplies?
甲、乙两个运输队要向地震灾区运送一批救灾物资，甲队每天能运送64.4吨，比乙队每天多运75%；如果甲、乙两队同时运送，当甲队运了全部救灾物资的1/2时，就比乙队多运了138吨．这批救灾物资一共有多少吨？
<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 + (3/4)</gadget>
<output>7/4 = around 1.75</output>

<gadget id="calculator">64.4 / (7/4)</gadget>
<output>36.8</output>

<gadget id="calculator">64.4 - 36.8</gadget>
<output>27.6</output>

<gadget id="calculator">138 / 27.6</gadget>
<output>5</output>

<gadget id="calculator">64.4 * 5</gadget>
<output>322</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">322 / (1/2)</gadget>
<output>644</output>

<result>644</result>