Salut !
5/6 + 1/2 = 5/6 + (1×3)/(2×3) = 5/6 + 3/6 = 8/6 = (4×2)/(3×2) = 4/3
3/5 + 7/10 = (3×2)/(5×2) + 7/10 = 6/10 + 7/10 = 13/10
8/3 + 1 = 8/3 + 1/1 = 8/3 + (1×3)/(1×3) = 8/3 + 3/3 = 11/3
4 + 3/4 = 4/1 + 3/4 = (4×4)/(1×4) + 3/4 = 16/4 + 3/4 = 17/4
5/9 - 2/3 = 5/9 - (2×3)/(3×3) = 5/9 - 6/9 = -1/9
7/6 - 13/30 = (7×5)/(6×5) - 13/30 = 35/30 - 13/30 = 22/30 = (2×11)/(2×15) = 11/15
2 - 4/7 = 2/1 - 4/7 = (2×7)/(1×7) - 4/7 = 14/7 - 4/7 = 10/7
8/9 - 5 = 8/9 - 5/1 = 8/9 - (5×9)/(1×9) = 8/9 - 45/9 = -37/9
