Answer:
I think this could be the answer- x^ +2x-15
You want to isolate the variable 'y'.

Subtract 10 to both sides:

Divide -3 to both sides:
Answer:
Step-by-step explanation:
Y = -x -1..........(1)
y = -2x + 7....(2)
Equating the two equations
-x -1 = -2x + 7
-x + 2x = 7+1
x = 8
Putting x in (1)
y = -8 - 1
y = -9