Răspuns :
Fie x-numarul.
x*2+45=65
x*2=65-45
x*2=20
x=20:2
x=10
Verificare:
10*2+45=20+45=65
x*2+45=65
x*2=65-45
x*2=20
x=20:2
x=10
Verificare:
10*2+45=20+45=65