Answer:
x= -3, y= 13
Explanation:
The idea is that x and y in both equations are the same numbers and that the equations are like rules that need to be followed both in the same time.
We take the y from one equation and use it in the other equation because is the same y .
3x+y =4 , subtract 3x from both sides
y= -3x+4
2x+y =7 , substitute y with the y = -3x+4 from the first equation
2x -3x+4 = 7, subtract 4 from both sides
2x-3x = 7-4, combine like terms
-x = 3 so x = -3
We know that x= -3 so we can substitute it in y= -3x+4 to find y
y= -3x+4
y= -3 (-3) +4
y= 9+4 = 13
y= 13