Part A: The right triangles are smiliar because If the lengths of the hypotenuse and a leg of a right triangle are proportional to the corresponding parts of another right triangle, then the triangles are similar.
Part B: 2z:2x or 2z/2x. You can write z/x as z:x. Then just multiply both sides by the same number to get an equivalent ratio. Let's multiply by 2. then the answer will be: 2z:2x or 2z/2x
