Grandma goes to the market to buy fruit. She first buys 2.5kg of peaches for 10.5 yuan, and is going to buy 1kg of grapes. The unit price of grapes is 1.5 times that of peaches. How much does it cost to buy grapes?
奶奶去市场买水果，她先花10.5元买了2.5kg桃子，还准备买1kg葡萄，葡萄的单价是桃子的1.5倍，买葡萄需要多少钱？
<gadget id="calculator">10.5 / 2.5</gadget>
<output>4.2</output>

<gadget id="calculator">4.2 * 1.5</gadget>
<output>6.3</output>

<result>6.3</result>