Question

[225-9×(80÷a+40)÷5]÷4+4=40

Answer 1

Răspuns:  a = 16

Explicație pas cu pas:

[ 225 - 9 × ( 80 : a + 40 ) : 5 ] : 4 + 4 = 40

[ 225 - 9 × ( 80 : a + 40 ) : 5 ] : 4 = 40 - 4

[ 225 - 9 × ( 80 : a + 40 ) : 5 ] : 4 = 36

225 - 9 × ( 80 : a + 40 ) : 5 = 36 × 4 = 144

9 × ( 80 : a + 40 ) : 5 = 225 - 144

9 × ( 80 : a + 40 ) : 5 = 81

9 × ( 80 : a + 40 ) = 81 × 5

80 : a + 40 = 405 : 9

80 : a + 40 = 45

80 : a = 45 - 40

a = 80 : 5

a = 16 → numarul, aflat prin metoda mersului invers