The school started to transfer 10 students. Director Li of the General Affairs Office went to buy 11 sets of desks and chairs. The chairs were 30 yuan each, and the price of each desk was twice that of the chairs.
开学了学校转进10名学生，总务处李主任去买了11套课桌椅，椅子每把30元，桌子每张价格是椅子的2倍，李主任买桌椅一共要付多少元．
<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<gadget id="calculator">30 + 60</gadget>
<output>90</output>

<gadget id="calculator">90 * 11</gadget>
<output>990</output>

<result>990</result>