There are 56 students in the third grade in a certain school, the number of the second grade is twice that of the third grade, and the number of the fourth grade is 53 less than the total number of the second and third grades. How many students are there in the fourth grade?
某校三年级有56人，二年级的人数是三年级的2倍，四年级的人数比二、三年级的人数总数少53人，四年级有多少人？
<gadget id="calculator">56 * 2</gadget>
<output>112</output>

<gadget id="calculator">56 - 53</gadget>
<output>3</output>

<gadget id="calculator">112 + 3</gadget>
<output>115</output>

<result>115</result>