Notez cu ,,a" numarul
[ ( 2 x a - 50 ) x 3 + 150 ] : 15 = 100
( 2 x a - 50 ) x 3 + 150 = 100 x 15
( 2 x a - 50 ) x 3 + 150 = 1 500
( 2 x a - 50 ) x 3 = 1 500 - 150
2 x a - 50 = 1 350 : 3
2 x a = 450 + 50
a = 500 : 2
a = 250 → numarul aflat prin metoda mersului invers
Verific:
[ ( 250 x 2 - 50 ) x 3 + 150 ] : 15 = ( 450 x 3 + 150 ) ; 15 = 1 500 : 15 = 100