department store buys a batch of toothbrushes at the wholesale price of 0.35 yuan each, and the retail price of 0.40 yuan each. When 200 toothbrushes are left, calculate the money you can buy minus the cost of all the purchases and you have made a profit of 100 yuan. How many toothbrushes do you buy in the store?
百货商店按批发价买进一批牙刷，每支0.35元，零售价每支0.40元．当卖剩200支牙刷时，计算买得得钱减去全部买进的成本已获利100元．商店买进牙刷多少支？
<gadget id="calculator">0.4 * 200</gadget>
<output>80</output>

<gadget id="calculator">100 + 80</gadget>
<output>180</output>

<gadget id="calculator">0.4 - 0.35</gadget>
<output>0.05</output>

<gadget id="calculator">180 / 0.05</gadget>
<output>3_600</output>

<result>3_600</result>