Question

aflați numărul necunoscut: {18-[(2×a-8):3-5]:3+12} :9+12=15
Va rog e urgent

Answer 1

{ 18 - [ ( 2 × a - 8 ) : 3 - 5 ] : 3 + 12 } : 9 + 12 = 15

{ 18 - [ ( 2 × a - 8 ) : 3 - 5 ] : 3 + 12 } : 9 = 15 - 12

18 - [ ( 2 × a - 8 ) : 3 - 5 ] : 3 + 12  = 3 × 9

18 - [ ( 2 × a - 8 ) : 3 - 5 ] : 3 = 27 - 12

[ ( 2 × a - 8 ) : 3 - 5 ] : 3 =18 - 15

[ ( 2 × a - 8 ) : 3 - 5 ] : 3 = 3

( 2 × a - 8 ) : 3 - 5  = 3 × 3

( 2 × a - 8 ) : 3 - 5  = 9

( 2 × a - 8 ) : 3 = 9 + 5

2 × a - 8  = 14 × 3

2 × a = 42 + 8

2 × a = 50

a = 50 : 2

a = 25 → numarul , aflat prin metoda mersului invers