Решите систему {x + 2y = -5; x + y = -3 {3x + 5y = 31; 5x +3y = 25

1)x=-3-y

-3-y+2y=-5

-y+2y=-5+3

y=-2

x=-3-(-2)=-3+2=-1

От:x=-1 y=-2

2) задача

5x=25-3y

x=(25-3y)/5

3(25-3y)/5+5y=31

3(25-3y)/5+5y×5=31×5

75-9y+25y=155

16y=80

y=80/16=5

x=(25-3×5)/5=(25-15)/5=10/5=2