两式左右分别相减，(A十A十A十B十B)-(A十B十B)=2A=6.5-5=1.5,A=0.75B=(5-0.75)/2=2.125
A十A十A十B十B=6.5,A十B十B=5。A=( 0.75)B=( 2.125)
