The garment factory originally planned to produce 90 sets of uniforms per day, but actually produced 120 sets per day, and finally completed 4 days ahead of schedule. How many sets of uniforms are there in this batch?
服装厂原计划每天生产90套制服，实际每天生产120套，最后比计划提前4天完成，这批制服有几套？
<gadget id="calculator">1 / 90</gadget>
<output>1/90 = around 0.011111</output>

<gadget id="calculator">1 / 120</gadget>
<output>1/120 = around 0.008333</output>

<gadget id="calculator">(1/90) - (1/120)</gadget>
<output>1/360 = around 0.002778</output>

<gadget id="calculator">4 / (1/360)</gadget>
<output>1_440</output>

<result>1_440</result>