Can someone help me im literally so confused

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.

What is the best way to answer questions with a x expression in the question. for example 3x + 10x=?

Complete the solution of the equation. find the value of y when x equals to 6 4x+y=20