1. a+b= 693,
a-b= b/4 =>
a=b/4+b=5b/4
5b/4+b=693=> 9b=2772=> b=308
a=693-308
a=385
2.
T+T/4 +3=173
4T/4+T/4=170
5T=680
T=136 timbre are Ancuta
3. a-b= 580.
a-20 =3*(b+20)
a-20=3b+60 => a=3b+80
3b+80-b=580
2b=500=>
b=250=>
a=580+250=+
a=830
4. a-b=80.
a/2:b/2=2 rest 10 => a:b=2 rest 20=> a=2b+20
2b+20-b=80
b=60
a=2*60+20=120+20
a=140