417 - 7a = bbb
b < 4
Varianta 1
b = 1
417 - 7a = 111
7a = 417 - 111
7a = 307
a = 307 : 7, nu convine
Varianta 2
b = 2
417 - 7a = 222
7a = 417 - 222
7a = 195
a = 195 : 7, nu convine
Varianta 3
b = 3
417 - 7a = 333
7a = 417 - 333
7a = 84
a = 84 : 7
a = 12, convine