15 × { 2 - [37 × 4 -3 × ( 45 - a ) - 288 : 18 ] } = 30
2 - [148 - 3 × ( 45 - a ) - 16 ] = 30 : 15
2 - [148 - 3 × ( 45 - a ) - 16 ] = 2
148 - 3 × ( 45 - a ) - 16 = 2 - 2
148 - 3 × ( 45 - a ) - 16 = 0
148 - 3 × ( 45 - a ) = 0 + 16
3 × ( 45 - a ) = 148 - 16
3 × ( 45 - a ) = 132
45 - a = 132 : 3
45 - a = 44
a = 45 - 44
a = 1 → numarul, aflat prin metoda mersului invers
