A stationery store bought a new batch of calculators and planned to price them at a profit of 40%. However, when there were only 40 units left, it was found that they had earned 30% of the total profit. How many calculators were there in this batch?
纠文具店新进一批计算器，计划以40%的利润定价，结果卖到还剩40个的时候发现已经赚了总利润的30%，这批计算器有多少个？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">40 * (2/5)</gadget>
<output>16</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(2/5) - (3/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">16 / (1/10)</gadget>
<output>160</output>

<result>160</result>