If y varies inversely with x and y = 8 when x = 10, then what is the constant of variation?

Which statement about perfect cubes is true

We just started the introduction into circles and i have no idea how to do this.

Find the least common multiple of the expressions: 1. 3x^2, 6x - 18 2. 5x, 5x(x +2) 3. x^2 - 9, x + 3 4. x^2 - 3x - 10, x + 2 explain if possible