I cutie /-------/-------/-------/
a II-a cutie /-------/
a III-a cutie /-------/ +18
a IV-a cutie /-------/-------/-------/ -15
un segment il notam cu A,
A=/-------/
total 875
avem 8 segmente,
8A + 18 -15 = 875
8A=875-18+15
8A=872
A=109,
I cutie are 3 segmente a, adica 3 x 109=327 culori
II cutie 109 culori
III cutie 109 + 18 =127 culori
IV cutie 3 x 109 -15=327-15=312 culori
proba: 327+109+127+312=875