AB = 15, AC = 4·BC, AC, BC - ?

Пусть BC = x, тогда AC = 4x. Так как AB = AC + BC, то:

4x + x = 15

5x = 15

x = 15 / 5

x = 3

BC = x = 3

AC = 4x = 4 * 3 = 12

Ответ: AC = 12, BC = 3