Find the solution of this system of equations -2x-4y=42 2x-8y=18

The hawaiian alphabet has 12 letters. how many permutations are posible for each number of letters?

In right ∆abc shown below, the midpoint of hypotenuse ac is located at d and segment bd is drawn.if ab = 12 and bc = 16, then explain why bd = 10. hint: consider what you know about the diagonals of a rectangle.

Can you me find the missing length. i attached an image.