Kidjov the answer I came up with for you is 792 I hope this helps
-x - 9

You want to get x by itself.
First subtract 9 from both sides of the equation.
-x - 9

+9 +9
-x

Then divide -1 on both sides.
-x/-1

I'm pretty sure when you divide a negative number when solving inequalities, you switch the sign.
x
Answer:
50 cm²
The answer is that because the area of a parallelogram is height × width.
height = 10cm
width = 5 cm
10 × 5= 50cm²