The Young Pioneers planted 64 trees in the third grade, twice as many trees in the fourth grade, and 42 fewer trees in the fifth grade than the sum of the third and fourth grades. How many trees does fifth grade plant?
少先队员植树造林，三年级种树64棵，四年级种的棵数是三年级的2倍，五年级种的棵数比三、四年级的总和还少42棵．五年级种树多少棵？
<gadget id="calculator">64 * 2</gadget>
<output>128</output>

<gadget id="calculator">128 - 42</gadget>
<output>86</output>

<gadget id="calculator">64 + 86</gadget>
<output>150</output>

<result>150</result>