The 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 there are 200 toothbrushes left unsold, the calculation deducts all costs and has made a profit of 200 yuan. How many toothbrushes do you buy in the store? (hint: solve with equations)
商店以批发价买进一批牙刷，每支0.35元，零售价每支0.40元，当还剩下200支没卖时，计算扣除所有成本已获利200元．商店买进牙刷多少支？(提示：用方程解)
<gadget id="calculator">0.4 * 200</gadget>
<output>80</output>

<gadget id="calculator">0.35 * 200</gadget>
<output>70</output>

<gadget id="calculator">200 - 70</gadget>
<output>130</output>

<gadget id="calculator">80 + 130</gadget>
<output>210</output>

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

<gadget id="calculator">210 / 0.05</gadget>
<output>4_200</output>

<result>4_200</result>