Using substitution:
first you have to express one variable in terms of the other, in this we can express y in terms of x:

Since both expressions are equal to y, you have to equal both expressions like this:

Now you can solve the equation:

Knowing x=10, you can use any of the expressions we found before to find y. In this case I'm going to use y= -x+9 because it's simpler but boy should give you the same result

So, the answer is x=10 and y=-1
This needs a graph to solve
Answer:
x=8
A = 192
Step-by-step explanation:
The perimeter is the sum of the outer lengths
17.9 + 22.6 + 3x = 64.5
Combine like terms
40.5 +3x = 64.5
Subtract 40.5 from each side
40.5 +3x -40.5 = 64.5 - 40.5
3x =24
Divide each side by 3
3x/3 = 24/3
x = 8
The area of a triangle is given by
A = 1/2 bh
The base is 3x = 3(8) =24
and the height is 2x = 2(8) =16
A = 1/2 (24) * 16
A =192