Alright, so first we'll have to get y on the other side
So
2x+y=-9
-y -y
+9 +9
2x+9=-y
Then divide is all by -1 so y is positive
-2x-9=y
Answer:
−1131
Step-by-step explanation:
20% = 0.20
50 * 0.20 = $10 discount
50 - 10 = 40
The price after 20% discount is $40
If you know that 
, then you know right away
###
Otherwise, you can derive the same result. Let 
, so that 
. 
is bounded, so we know 
. For these values of 
, we always have 
.
So, recalling the Pythagorean theorem, we find
Then
as expected.
