Xiaoqiang's average score in Chinese, mathematics and English in the final exam is 91, and his average score in Chinese and English is 87. How many points did he score in mathematics?
小强期末考试语文、数学、英语的平均成绩是91分，语文和英语的平均成绩是87分，他数学得了多少分？
<gadget id="calculator">91 * 3</gadget>
<output>273</output>

<gadget id="calculator">87 * 2</gadget>
<output>174</output>

<gadget id="calculator">273 - 174</gadget>
<output>99</output>

<result>99</result>