The students planted trees. The fifth grade students planted 45 trees, and the sixth grade students planted twice as many trees as the fifth grade students. How many trees did the sixth grade students plant?
同学们栽树，五年级同学栽了45棵，六年级同学栽的棵数是五年级的2倍还多9棵，六年级同学栽多少棵？
<gadget id="calculator">45 * 2</gadget>
<output>90</output>

<gadget id="calculator">90 + 9</gadget>
<output>99</output>

<result>99</result>