Răspuns :
a + b + c = 92
a + b = 63
b + c = 65
c = 92 - 63
c = 29
b = 65 - c
b = 65 - 29
b = 36
a = 63 - b
a = 63 - 36
a = 27
I+II+III=92
I+II=63
II+III=65
63+III=92 /-
III=29 ( pagini a 3 a zi )
II+29=65 /-
II=36 ( pagini a 2 a zi )
I+36=63 /-
I=27 ( pagini in prima zi )