The price of a bottle of ink is 3.6 yuan, and the price of a pen is 0.9 yuan more than ink. How much is it to buy a pen and a bottle of ink?
一瓶墨水的价钱是3.6元，一枝钢笔的价钱比墨水贵0.9元，买一枝钢笔和一瓶墨水多少元？
<gadget id="calculator">3.6 + 0.9</gadget>
<output>4.5</output>

<gadget id="calculator">3.6 + 4.5</gadget>
<output>8.1</output>

<result>8.1</result>