Convert a mixed number to an improper fraction in lowest terms.

To convert the mixed number $2\frac{2}{8}$ to an improper fraction, multiply the whole number by the denominator and add the numerator: $(2 \times 8) + 2 = 18$. The denominator remains 8, so the improper fraction is $\frac{18}{8}$. Simplify this fraction by dividing both numerator and denominator by their greatest common divisor, which is 2: $\frac{18 \div 2}{8 \div 2} = \frac{9}{4}$.