Let's reduce: $\frac{8+4}{4}$

ⓘ The numerator and the denominator are computed before the division: $8+4$ = $12$

$\frac{12}{4}$

ⓘ We simplify the fraction by dividing the numerator and the denominator by $4$, their greatest common divisor: $\frac{12}{4}$ = $3$

▶Simplified form:   $3$