Răspuns :
[( a : 5 ) x 2] : 4 +5 = 9
[( a ; 5 ) x 2 ]: 4 = 9 - 5 = 4
( a : 5 ) x 2 = 4 x4 = 16
a : 5 = 16 : 2 = 8
a : 5 = 8
a = 8 x5
a = 40
[( a ; 5 ) x 2 ]: 4 = 9 - 5 = 4
( a : 5 ) x 2 = 4 x4 = 16
a : 5 = 16 : 2 = 8
a : 5 = 8
a = 8 x5
a = 40