Record the average height of Xiao Ming, Xiao Hong, and Xiao Fang as 0, Xiao Hong's height as +5 cm, Xiao Ming's height as -2 cm, how many centimeters is the difference between Xiao Hong and Xiao Ming's height.
把小明、小红、小芳的平均身高记为0，小红的身高记为+5厘米，小明的身高记为-2厘米，小红和小明的身高相差多少厘米．
<gadget id="calculator">5 - (-2)</gadget>
<output>7</output>

<result>7</result>