Idon't know how to do this can some one give me step by step instructions (geometry) we have to find the value of x .tell which theorem in use

In triangle abc segment de is parallel to the side ac . (the endpoints of segment de lie on the sides ab and bc respectively). find de, if ac=20cm, ab=17cm, and bd=11.9cm;

Each of the walls of a room with square dimensions has been built with two pieces of sheetrock, a smaller one and a larger one. the length of all the smaller ones is the same and is stored in the variable small. similarly, the length of all the larger ones is the same and is stored in the variable large. write a single expression whose value is the total area of this room. do not use any method invocations.

To which set of numbers does the number –5 belong? select all that apply. integers natural numbers rational numbers real numbers whole numbers