The students carried water to water the trees. The third grade watered 50 trees, the fourth grade watered 30 more trees than the third grade, and the fifth grade watered twice as many trees as the fourth grade. How many trees did the fifth grade water?
同学们抬水浇树，三年级浇了50棵，四年级比三年级多浇30棵，五年级浇的棵数等于四年级的2倍，五年级浇了多少棵？
<gadget id="calculator">50 + 30</gadget>
<output>80</output>

<gadget id="calculator">80 * 2</gadget>
<output>160</output>

<result>160</result>