Define the operation "△" as follows: For two natural numbers a and b, the sum of their greatest common divisor and least common multiple is denoted as a△b. For example: 4△6=(4,6)+(4,6)=2+12=14. According to the calculation defined above, 18△12=how much.
定义运算"△"如下：对于两个自然数a和b，它们的最大公约数与最小公倍数的和记为a△b．例如：4△6=(4，6)+(4，6)=2+12=14．根据上面定义的运算，18△12=多少．
<result>42</result>