` a) ` ` \frac{32 × 50}{48 × 75} `
` = \frac{8 × 2 × 2 × 25 × 2}{8 × 2 × 3 × 25 × 3} `
` = \frac{2 × 2}{3 × 3} `
` = 4/9 `
` b) ` ` \frac{63 × 81}{135 × 84} `
` = \frac{9 × 7 × 3 × 3 × 3 × 3}{9 × 3 × 5 × 7 × 3 × 4} `
` = \frac{3 × 3}{5 × 4} `
` = \frac{9}{20} `