Final answer:
To combine the given expression into a single fraction, find a common denominator for the two fractions and simplify the expression. The value of a is -2 and the value of b is 12.
Step-by-step explanation:
To combine the given expression into a single fraction, we need to find a common denominator for the two fractions.
The common denominator will be the product of the denominators, which in this case is (x-4)(x+4).
We then multiply each fraction by its missing factor to get a common denominator:
(2-(x+3)/(x-4)) * (x+4)/(x+4) - (x-7)/(x+4) * (x-4)/(x-4)
Simplifying further, we get (2x+8-x-3-x+7)/(x^2-16).
Combining like terms, the numerator becomes (-2x+12)/(x^2-16).
Therefore, the value of a is -2 and the value of b is 12.