Solve the system by adding or subtracting
-3x-3y=9
3x+8y=6

x = -6 y = 3

Step-by-step explanation:

Adding the two equations and you get, -3x-3y + 3x+8y= 6+9

=> 5y = 15

=> y = 3

Plug y in each equation

-3x -3(3) = 9

-3x -9 = 9

-3x = 18

x = -6

3x + 8(3) = 6

3x +24 = 6

3x = -18

x = -6

final answer is : )

(b) 240

step-by-step explanation:

first, we use the pythagorean formula using the given side lengths to find x. then we use x to find the side lengths. then we add the side lengths to find the perimeter.

pythagorean theorem formula:

a^2 + b^2 = c^2

(x - 20)^2 + (x - 40)^2 = x^2

x^2 - 40x + 400 + x^2 - 80x + 1600 = x^2

x^2 -120x + 2000 = 0

(x - 100)(x - 20) = 0

x - 100 = 0 or x - 20 = 0

x = 100 or x = 20

we see that the solution x = 20 must be discarded because it will give a negative side length and a side length of 0. the only valid solution is x = 100.

perimeter = sum of the lengths of the sides

perimeter = x + x - 20 + x - 40

perimeter = 3x - 60

replace x with 100.

perimeter = 3(100) - 60

perimeter = 300 - 60

perimeter = 240