Unanswerable question unless you mistyped CAB as DAB.
To find the length of the span of a proposed ski lift from A to B, a surveyor measures the angle DAB to be 25 degrees and then walks a distance of 1000 feet to C and measures angle ACB to be 15 degrees. What is the distance from A to B?
If you want to draw using a computer keyboard, then get some graphics software. When I suggest "draw a picture" I mean using a piece of paper and a pencil. The plan being that this will help you see what the problem is and then you might be able to solve it straight away.
As for this problem you're describing, does a diagram come with it to explain where A, B, C, D are in relation to each other? Unless we have some idea of the spatial relationship between C and D it is impossible to tell where C is.
You say "walks a distance of 1000 feet" to C - in what direction?
Get a piece of paper and draw a line representing 1000 ft (which is AC).
Draw a line at 15 degrees to this. All we know is that on that second line there is a point B which (from the definition of the question) could be *anywhere*. Unless there's some other information somewhere, for example, how far it is from B to C, or what the angle ABC is, you can't solve this problem.
Are you sure there is no more information in the question beyond what you've given? Is there a diagram there, for example?
If not, then the question can not be done and the book is rubbish. If there is then tell me what it is, or I'm not wasting any more time on this.
What book is it? Maybe someone out there will have a copy and be able to take this problem on.