Hey there! Hello!

So, lets expand this problem. The distributive property basically states that multiplying two numbers being added together is the same as multiplying the outer number by the two numbers being added individually, then adding those together. Sounds way harder than it is:

x(y+z) = xy+xz

You can apply this to your problem like this: multiply the 4 by each term in your binomial (your two terms in parenthesis), then simplify. 

4(x-1) = 4x-(4)(-1)= 4x-(-4)

(One thing to always remember – at least, in terms of algebra and not necessarily life – two negatives always equal a positive. This is not shown above, however, because the symbol on the end of the given problem is a subtraction sign. Your answer, in this case, is (–4), or B. Hope that clears up any confusion). 

Hope this helped you out! Feel free to ask me any questions if you need further clarification. 🙂