Although you didn't provide any answer choices:
A trinomial is an expression with exactly three terms that can't be combined an example would be this
x^2 - 3x + 1
None of those terms can be combined
x^2 + 3 - 4 has three terms but it isn't considered a trinomial because you can simplify it to x^2 - 1 which is known as a binomial because it has 2 terms in it's simplified form.
hope this helps C:
It is $6 more now than before...maybe you were looking for percent increase?
%change=100(final-initial)/initial
%change=100(10-4)/4=150% increase
The answer is b because it is equivalent.
The answer is has to be D