Mom wants to buy some fruit with 50 yuan. She first bought 3 kilograms of grapes for 27.9 yuan, and planned to use the remaining money to buy some apples at 8.5 yuan per kilogram. How many kilograms of apples did mom buy? What other math questions can you ask? Try to figure it out.
妈妈要用50元钱买一些水果．她先花27.9元买了3千克葡萄，并准备用剩下的钱买一些苹果，每千克苹果8.5元．妈妈买了几千克苹果？你还能提出什么数学问题？试着解答出来．
<gadget id="calculator">27.9 / 3</gadget>
<output>9.3</output>

<gadget id="calculator">9.3 - 8.5</gadget>
<output>0.8</output>

<result>0.8</result>