Помогите решить системы уравнений

3x+1=8y

11y-3x=11

2x+y=12

7x-2y=31

3x+1=8y 3x - 8y = - 1

11y-3x=11 - 3x + 11y = 11

3y = 10 y = 10 / 3

x = (8y - 1) / 3 = ((80 / 3) - 3 / 3) / 3 = 77 / 9 = 8 (5/9)

2x+y=12 4x + 2y = 24

7x-2y=31 7x - 2y = 31

11x = 55 x = 55 / 1 = 5

y = 12 - 2x = 12 - 2*5 = 12 - 10 = 2