Final answer:
The question does not provide sufficient information to determine the length of d. More context such as a diagram or additional measurements would be required to find d and round it to the nearest tenth.
Step-by-step explanation:
The question provided doesn't give enough information or context to solve for the length of d. Typically, to find a length in geometry, a relationship or formula needs to be provided that connects d with the other given measurements, such as w, h, and x. From the information given, it seems there may be a scale drawing or geometric shape involved, but with the current details, the problem is incomplete. If more context or a diagram was provided, then it would be possible to set up a proportion or use a geometric property or theorem to find the value of d, round it to the nearest tenth, and complete the question as asked.