Which expression is equivalent to 13b+23b−56(b+1)?

Start by combining LIKE-TERMS. 13b AND 23 are LIKE-TERMS because they have the same variable (B) and numbers. Remember PEMDAS OR Please Excuse My Dear Aunt Sally. (Parentheses, Exponents, Multiplication, Division, Addition, Subtraction). There is also FOIL (First, Inside, Outside, Last). Because we will start with Parenthesis(Use the FOIL method because the 56 is part of the parentheses) first, (-56 x b[first part of the set]) = -56b  THEN (-56 x [+ {always carry the sign, this shows that it is positive}]1) = -56

Now we have 13b+23b -56b-56
                     =36b        -56b -56
                     = -20b    - 56
       This is your final equation because THESE ARE NOT LIKE-TERMS, therefore, they CANNOT be combined

So, your answer to this problem is -20b - 56.