[ ( 2 x - 100 ) : 3 + 100 ] : 2 = 100
( 2 x - 100 ) : 3 + 100 = 100 × 2
( 2 x - 100 ) : 3 + 100 = 200
( 2 x - 100 ) : 3 = 200 - 100
( 2 x - 100 ) : 3 = 100
2 x - 100 = 100 × 3
2 x - 100 = 300
2 x = 300 + 100
2 x = 400
x = 400 : 2
x = 200 → numarul, aflat prin metoda mersului invers
