[ 11 + ( a + 109 × 9 - 903 ÷ 3 ) ÷ 9 ] × 5 + 1618 = 2018
[ 11 + ( a + 981 - 301 ) ÷ 9 ] × 5 + 1618 = 2018
[ 11 + ( a + 680 ) ÷ 9 ] × 5 + 1618 = 2018 / - 1618
[ 11 + ( a + 680 ) ÷ 9 ] × 5 = 400 / ÷ 5
11 + ( a + 680 ) ÷ 9 = 80 / × 9
11 + ( a + 680 ) = 720 / - 11
a + 680 = 709
a = 709 - 680
a = 29
Răspuns : 29
Succes!