Question

Afla numarul necunoscut la operatia 7+6*(5+2*a):5=25

Answer 1

7 + 6 × ( 5 + 2 × a ) : 5 = 25

6 × ( 5 + 2 × a ) : 5 = 25 - 7

6 × ( 5 + 2 × a ) : 5 = 18

6 × ( 5 + 2 × a ) = 18 × 5

6 × ( 5 + 2 × a ) = 90

5 + 2 × a = 90 : 6

5 + 2 × a = 15

2 × a = 15 - 5

2 × a = 10

a = 10 : 2

a = 5 → numarul necunoscut, aflat prin metoda mersului invers