Răspuns :
d= 80 - 64
d= 16
c + c = d
8 + 8 = 16
c = 8
b + b = 8
4 + 4 = 8
b = 4
a + a = b
a + a = 4
2+2 = 4
a= 2
d= 16
c + c = d
8 + 8 = 16
c = 8
b + b = 8
4 + 4 = 8
b = 4
a + a = b
a + a = 4
2+2 = 4
a= 2