Master Zhang buys apples at a price of 1 yuan and 3 apples, and sells them at a price of 2 yuan and 5 apples. If he wants to make a profit of 10 yuan, how many apples must he sell? apple?
张师傅以1元3个苹果的价格买进苹果若个个，又以2元5个苹果的价格将这些苹果卖出去，如果他要赚得10元钱利润，那他必须卖出多少个苹果？
<gadget id="calculator">6 - 5</gadget>
<output>1</output>

<gadget id="calculator">10 / 1</gadget>
<output>10</output>

<gadget id="calculator">10 * 15</gadget>
<output>150</output>

<result>150</result>