Each worker and equipment of two garment factories A and B can fully produce suits of the same specification. Factory A takes (3/5) time to produce jackets and (2/5) time to produce trousers every month, producing exactly 900 suits in a whole month; factory B takes (4/7) time to produce jackets every month, (3 /7) produces pants, and produces exactly 1200 suits in the whole month. Now the two factories jointly produce and try to make use of their respective strengths to produce more suits, so how many more suits are produced every month than in the past?
甲、乙两个服装厂每个工人和设备都能全力生产同一规格的西服．甲厂每月用(3/5)的时间生产上衣，(2/5)的时间生产裤子，全月恰好生产900套西服；乙厂每月用(4/7)的时间生产上衣，(3/7)的时间生产裤子，全月恰好生产1200套西服．现在两厂联合生产，尽量发挥各自特长多生产西服，那么现在每月比过去多生产西服多少套？
<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1_200 / (4/7)</gadget>
<output>2_100</output>

<gadget id="calculator">1_200 / (4/7) / 900</gadget>
<output>7/3 = around 2.333333</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(7/3) * (2/5)</gadget>
<output>14/15 = around 0.933333</output>

<gadget id="calculator">1 - (14/15)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">900 * (1/15)</gadget>
<output>60</output>

<gadget id="calculator">2_100 + 60</gadget>
<output>2_160</output>

<gadget id="calculator">1_200 + 900</gadget>
<output>2_100</output>

<gadget id="calculator">2_160 - 2_100</gadget>
<output>60</output>

<result>60</result>