Solve with subsitution x+y=1, 2x+3y=-4

{   x + y = 1    * ( - 2 )
  2 x + 3y = -4

- 2 x - 2 y = - 2
  2 x + 3 y = - 4

         y = - 6

Subsititute y = - 6 

2 x + 3 y = - 4

2 x + 3 * (-6) = -4

2 x - 18 = - 4

2 x = - 4 + 18

2 x = 14

x = 14 / 2

x = 7

The solution  to the system of equations are:

x = 7 and y = - 6

hope this helps!

That. you would have multiple