Answer: It has one solution. The solution is (x,y) = (-4,-3)
Add up the equations doing so straight down
x + -x = 0x = 0 so the x terms go away
2y + 2y = 4y
-10 + (-2) = -12
We end up with 4y = -12 so y = -3 after you divide both sides by 4. Use this y value to find the value of x
x+2y = -10
x + 2(-3) = -10
x - 6 = -10
x = -10+6
x = -4
The single solution is (x,y) = (-4,-3)
As a check, plug this solution into each equation to see if you get a true statement or not. Let's do so with the first equation
x+2y = -10
-4 + 2(-3) = -10
-4 - 6 = -10
-10 = -10 .... true
and then the second equation
-x+2y = -2
-(-4) + 2(-3) = -2
4 - 6 = -2
-2 = -2 .... true
both equations are true, so the solution is confirmed
F(x) = -5x - 4
g(x) = 6x - 7
f(x) + g(x) = (-5x-4) + (6x-7)
f(x) + g(x) = x - 11
your answer would be 13.5
