Answer: 
Step-by-step explanation:
Observe in the figure given in the exercise that four right triangles are formed.
In this case you can use the following Trigonometric Identity to solve this exercise:
From the figure you can identify that:

Then, you can substitute values:

The next step is to solve for DE in order to find its value. This is:

Finally, rounding the result to the nearest tenth, you get that this is:

Basically the real one is 80 times the picture
80 times 3/4=80/1 times 3/4=240/4=60in=5ft
it is 5ft long or 60in
Answer:
3 n minus 4 represents the expression "four less than three times a number"