Divide a rope into two sections A and B. Section A is 30 meters long and section B is twice as long as A. How long is this rope in decimeters?
把一条绳子分成A、B两段，A段长30米，B段长是A的2倍．这条绳子长是多少分米？
<gadget id="calculator">30 * 2</gadget>
<output>60</output>

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

<gadget id="calculator">90 * 10</gadget>
<output>900</output>

<result>900</result>