Răspuns :
x-numarul natural
{[(x+5)*5]-5}:5=5 desfacem pe rand parantezele
[(x+5)*5]-5=25
(x+5)*5=30
x+5=6
x=6-5
x=1
{[(x+5)*5]-5}:5=5 desfacem pe rand parantezele
[(x+5)*5]-5=25
(x+5)*5=30
x+5=6
x=6-5
x=1
Fie a-nr.
{[(a+5)*5]-5}:5=5
[(a+5)*5]-5=5*5
[(a+5)*5]-5=25
(a+5)*5=25+5
(a+5)*5=30
a+5=30/5
a+5=6
a=6-5
a=1
{[(a+5)*5]-5}:5=5
[(a+5)*5]-5=5*5
[(a+5)*5]-5=25
(a+5)*5=25+5
(a+5)*5=30
a+5=30/5
a+5=6
a=6-5
a=1