Fraction Addition - Insight

To add fractions $\frac{a}{b} + \frac{c}{d}$, you need a common denominator. The result is $\frac{a \times d + c \times b}{b \times d}$.

After adding, simplify by dividing both numerator and denominator by their GCD. This gives the fraction in lowest terms.

Critical: Handle negative signs carefully. The GCD is always positive, so track the sign separately in the numerator.