Bonjour,
4/3 × 7/5 = (4×7)/(3×5) = 28/15
1/5 × 1/8 = (1×1)/(5×8) = 1/40
4/5 × 7/3 = (4×7)/(5×3) = 28/15
4/7 × 4/3 = (4×4)/(7×3) = 16/21
7/5 × 7/5 = (7×7)/(5×5) = 49/25
7 × 3/10 = 7/1 × 3/10 = (7×3)/(1×10) = 21/10
1/2 × 3/5 × 7/4 = (1×3×7)/(2×5×4) = 21/40
5 × 1/7 × 8/3 = 5/1 × 1/7 × 8/3 = (5×1×8)/(1×7×3) = 40/21
