There are 136 color TV sets of A and B types in a shopping mall. During the National Day promotion, 57 sets of A color TVs (2/5) and B color TVs (3/7) were sold. How many A-type color TVs were sold?
某商场有A，B两种型号的彩电136台，国庆促销活动中，卖出A型号彩电的(2/5)和B型号彩电的(3/7)，共卖出57台．卖出A型号彩电多少台．
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(3/7) * 136</gadget>
<output>408/7 = around 58.285714</output>

<gadget id="calculator">(408/7) - 57</gadget>
<output>9/7 = around 1.285714</output>

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

<gadget id="calculator">(3/7) - (2/5)</gadget>
<output>1/35 = around 0.028571</output>

<gadget id="calculator">(9/7) / (1/35)</gadget>
<output>45</output>

<gadget id="calculator">45 * (2/5)</gadget>
<output>18</output>

<result>18</result>