It is known that Xiao Ming is 12 years old this year, and Xiao Hua is 15 years old this year. After 3 years, how much older will Xiao Ming be than Xiao Hua?
已知小明今年12岁，小华今年15岁，3年后，小明比小华大多少岁．
<gadget id="calculator">15 - 12</gadget>
<output>3</output>

<result>3</result>