Răspuns :
ab + ac + a = 165
ab + ac = 165 - a
a x (b + c) = 165 - a
dar b + c = 10
a x 10 = 165 - a
10a + a = 165
11 a = 165
a = 165 / 11
a = 15
ab + ac = 165 - a
a x (b + c) = 165 - a
dar b + c = 10
a x 10 = 165 - a
10a + a = 165
11 a = 165
a = 165 / 11
a = 15