and b represent two different natural numbers, decomposed prime factor a=2*5*c, b=3*5*c, if the least common multiple of a and b is 60, then what is c equal to.
a和b表示两个不同的自然数，分解质因数a=2*5*c，b=3*5*c，如果a和b的最小公倍数是60，那么c等于多少．
<result>2</result>