Răspuns :
15 ─ ( 8 + 4 x a) : 5 = 11
( 8 + 4 x a) : 5 = 15 – 11
( 8 + 4 x a) : 5 = 4
8 + 4 x a = 4 x 5
8 + 4 x a = 20
4 x a = 20 – 8
4 x a = 12
a = 12 : 4
a = 3).
( 8 + 4 x a) : 5 = 15 – 11
( 8 + 4 x a) : 5 = 4
8 + 4 x a = 4 x 5
8 + 4 x a = 20
4 x a = 20 – 8
4 x a = 12
a = 12 : 4
a = 3).