a*6:9=a*2:3=72
=> a*2=72*3
=>a=216:2
=>a=108
300-(2*a+57)=131
=>300-131=2*a+57
=> 169-57=2*a
=> a=112/2
a=56
a:8:5=5
=> a=5*5*8
a=200
(a*4+51)-203=20
=> a*4+51=203+20
a*4=223-51
a=172:4
a=43
a:2+43-(200-56):6=35-----(inmultim totul cu 6)
=> a*3+43*6-144=35*6
=>a*3+258-144=210
=>a*3=210+144-258
a=96:3
a=32
