Răspuns:
Explicație pas cu pas:
12×[(5×a-6):7+23]:4-15+3=63
12×[(5×a-6):7+23]:4-15 = 63 - 3 = 60
12×[(5×a-6):7+23]:4 = 60 + 15 = 75
12×[(5×a-6):7+23] = 75×4 = 300
(5×a-6):7+23 = 300 : 12 = 25
(5×a-6):7 = 25 - 23 = 2
5×a-6 = 2×7 = 14
5×a = 14 + 6 = 20
a = 20 : 5 = 4