Ответ:

x1 = 1

x2 = 2.5

x3 =  5

Пошаговое объяснение:

(x1 + x2 + x3 ) / 3 = 2.5

x2 = x1 + 1.5

x3 = x2 * 2

(x1 + x1+1.5 + (x1 +1.5)*2)/3=2.5

4x1+3.5=7.5

4x1=4

x1 = 1

x2 = 1 + 1.5 = 2.5

x3 = 2.5 * 2 = 5