Originally, the number A is 2.1 more than the number B. If the number A decreases by 1.2 and the number B increases by 1.2, how much is the number A greater than the number B?
甲数原来比乙数多2.1，如果甲数减少1.2、乙数增加1.2，这时甲数比乙数多少．
<result>0.3</result>