Plz Help I dont understand this. solve for y and x Substitution Method.

1) 2x + 8y = 20 2) x = 5
y = 2 2x + y = 10

Is the square root of 4 plus the square root of 16 rational?

If y varies directly as x2 and y=6 when x=6, find the constant of variation.

Someone answer asap for ! a ball is rolled down a ramp. the height, f(x), in meters, of the ball x seconds after it is released is modeled by the function f(x) = x²- 10x + 25 for all values of x from 0 to 5. which statement about the ball is true? a. the maximum height of the ball is 5 meters b. the height of the ball increases from 0 to 5 meters above the ground. c. the ball has traveled 5 meters when it reaches the bottom of the ramp. d. the ball has been traveling for 5 seconds when it reaches the bottom of the ramp