Geometry: how do you know if a triangle is a dilation of another triangle?

(98 points) i need with 5 questions. answer definitions are welcomed, but not necessary.

What is the anwers for 9+2x=5x-3-x

Look at the figure below: triangle abc is a right triangle with angle abc equal to 90 degrees. the length of ac is 5 units and the length of ab is 4 units. d is a point above c. triangle adc is a right triangle with angle dac equal to 90 degrees and dc parallel to ab. what is the length, in units, of segment cd?