rational expressions

How is multiplying/dividing rational expressions similar to multiplying/dividing fractions?  How is adding/subtracting rational expressions similar to adding/subtracting fractions?2. How do you solve rational equations?3. In the rational expression, 4x ? 8×2+4x ?12 , why is it incorrect to cancel the 4x in the numerator with the 4x in the denominator?  How would you correctly simplify this rational expression?