(a+b) / 2 = 23
a+b=46
a+25%=a+25/100=125a/100
b+20%=b+20/100=120b/100
[125a/100+120b/100] : 2 =28
(125a+120b) : 100=56
125a+120b=5600
a+b=46
a=46-b
125(46-b)+120b=5600
5750-125b+120b=5600
5750-5600=125b-120b
150=5b
b = 30
a=46-30=16
a = 16
proba:
(16+30) : 2 = 23
16+25%= 20
30+20%= 36
( 20+36):2=56:2=28