1. **State the problem:** We need to find the area of a trapezoid with the following dimensions: - Top base $b_1 = 1$ km - Bottom base $b_2 = 1 \frac{5}{8}$ km - Height $h = 1 \frac{7}{9}$ km 2. **Convert mixed numbers to improper fractions:** - $1 \frac{5}{8} = \frac{8}{8} + \frac{5}{8} = \frac{13}{8}$ km - $1 \frac{7}{9} = \frac{9}{9} + \frac{7}{9} = \frac{16}{9}$ km 3. **Recall the formula for the area of a trapezoid:** $$ Area = \frac{1}{2} \times (b_1 + b_2) \times h $$ 4. **Substitute the values:** $$ Area = \frac{1}{2} \times \left(1 + \frac{13}{8}\right) \times \frac{16}{9} $$ 5. **Add the bases:** $$ 1 + \frac{13}{8} = \frac{8}{8} + \frac{13}{8} = \frac{21}{8} $$ 6. **Calculate area:** $$ Area = \frac{1}{2} \times \frac{21}{8} \times \frac{16}{9} = \frac{21}{16} \times \frac{16}{9} $$ 7. **Simplify:** The $16$s cancel out: $$ Area = \frac{21}{9} = \frac{7}{3} $$ 8. **Convert to mixed number:** $$ \frac{7}{3} = 2 \frac{1}{3} $$ **Final answer:** The area of the trapezoid is $2 \frac{1}{3}$ square kilometres.