afla numarul x din egalitatea[(2x-100):3+100]:2=100

[ ( 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