The school organizes math competitions, 28 in the third grade, twice as many in the fourth grade, and 18 fewer in the fifth grade than in the fourth grade. How many people participated in the math competition in the fifth grade?
学校组织数学竞赛，三年级有28参加，四年级参加的人数是三年级的2倍，五年级参加的人数比四年级少18人．五年级参加数学竞赛的有多少人？
<gadget id="calculator">28 * 2</gadget>
<output>56</output>

<gadget id="calculator">56 - 18</gadget>
<output>38</output>

<result>38</result>