Răspuns :
a-b=28
b=3/10*a=3a/10
a-3a/10=28
10a/10-3a/10=28
7a/10=28
7a=28*10
a=280:7
a=40
40-b=28
-b=28-40
b=12
b=3/10*a=3a/10
a-3a/10=28
10a/10-3a/10=28
7a/10=28
7a=28*10
a=280:7
a=40
40-b=28
-b=28-40
b=12