1. If a,b ,c ,d and are four different digits from 1 to 9 , inclusive, then what's the largest possible value for the decimal a.b + c.d?
9.8 + 7.6 = 17.4
2. If a,b ,c ,d and are four different digits from 1 to 9 , inclusive, then what's the largest possible value for the decimal a.b - c.d?
9.8 - 1.2 = 8.6