A pencil is 1.7 yuan, and a pen is 4.5 yuan more expensive than a pencil. How much money does it cost to buy a pencil and a pencil?
一支铅笔1.7元，一支钢笔比一支铅笔贵4.5元．买一支铅笔和一支铅笔一共需金多少元？
<gadget id="calculator">1.7 + 4.5 + 1.7</gadget>
<output>7.9</output>

<result>7.9</result>