Răspuns :
nr timbre alin=a
nr timbre vlad=b
a=7+b/2
7+b/2+b=67
=>b/2+b=60=> 3b/2=60 => b/2=20=> b=40 timbre
a=7+20=27
nr timbre vlad=b
a=7+b/2
7+b/2+b=67
=>b/2+b=60=> 3b/2=60 => b/2=20=> b=40 timbre
a=7+20=27