Ответ:

a-b=2 => a = 2+b

4a+2b-5c = 8 => 8 + 4b - 5c = 8  = 4b - 5c = 0

a+ 2c = 19  =>  2 + b + 2c = 19  => b + 2c = 17.

4b - 5c = 0

b + 2c = 17 /*4  => 4b + 8c = 68

.

4b - 5c = 0

4b + 8c = 68

-

-5c - 8c = -68

-13c = -68

c = 68/13

.

4b + 8c = 68 => 4b + 8*68/13 =68 => 4b * 13 = 68 * (13 - 8) => b = 68 * 5/(13*4)

a = 2 + b =>  a = 2 + 68 * 5/(13*4) = a = 13*4*2 + 68 * 5.

Пошаговое объяснение: