ж) 4/5 × 5 = 4/5 × 5/1 = 20/5 = 4
з) 5/9 × 1/5 = (5 × 1) / (9 × 5) = 5 / 45 = 1/9
и) 1 1/3 × 3/4 = (3/3 + 1/3) × 3/4 = 4/3 × 3/4 = 12/12 = 1
ж) 4/5 × 5 = 4/5 × 5/1 = 20/5 = 4
з) 5/9 × 1/5 = (5 × 1) / (9 × 5) = 5 / 45 = 1/9
и) 1 1/3 × 3/4 = (3/3 + 1/3) × 3/4 = 4/3 × 3/4 = 12/12 = 1