Xiao Ming went to a department store last week and bought 2 pens and 4 pencils for 30 yuan. When I went to the department store this week, I found that the price of pens was reduced by 10% and the price of pencils was increased by 20%. So Xiao Ming spent another 30 yuan to buy 3 pens and 1 pencil. How much does it cost to buy 1 pen and 1 pencil now?
小明上周去百货商店用30元买了2支钢笔和4支铅笔．这周去百货商店时，发现钢笔降价10%，铅笔加价20%．于是，小明又花了30元买了3支钢笔和1支铅笔．现在买1支钢笔和1支铅笔一共需要多少元．
<gadget id="calculator">2.5 * 2</gadget>
<output>5</output>

<gadget id="calculator">15 - 5</gadget>
<output>10</output>

<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">10 * (9/10)</gadget>
<output>9</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">2.5 * (6/5)</gadget>
<output>3</output>

<gadget id="calculator">9 + 3</gadget>
<output>12</output>

<result>12</result>