甲×4/5=乙×1/2
甲=乙×1/2×5/4
甲=乙×5/8=乙×62.5%
(乙-甲)/甲=(1-5/8)/(5/8)=3/5=60%
答:甲数的五分之四等于乙数的二分之一.甲数是乙数的( 62.5 )%,乙数比甲数多( 60 )%