a,b,c,d,e- cele 5 zile => inseamna arezulta
a-x probleme
b=x+2 probleme
c=x+4 probleme
d=x+6 probleme
e=x+8 probleme
a+b+c+d+e= 45 probleme=> x+x+2+x+4+x+6+x+8=45
=>5x+20=45
=>5x=45-20
=>5x=25 probleme
=>x=25:5
=>x=5 pproblme
in prima zi a rezolvat 5 probleme adica a=5 probleme , iar in a treia zi a rezolvat 9 adica c=5+4, c=9 probleme