Răspuns: x = 7
Explicație pas cu pas:
[ 5 × ( 5 × x - 5 ) - 120 ] × 5 - 25 = 125
[ 5 × ( 5 × x - 5 ) - 120 ] × 5 = 125 + 25
[ 5 × ( 5 × x - 5 ) - 120 ] × 5 = 150
5 × ( 5 × x - 5 ) - 120 = 150 : 5
5 × ( 5 × x - 5 ) - 120 = 30
5 × ( 5 × x - 5 ) = 30 + 120
5 × ( 5 × x - 5 ) = 150
5 × x - 5 = 150 : 5
5 × x - 5 = 30
5 × x = 30 + 5
5 × x = 35
x = 35 : 5
x = 7