bjr
3/5 + 1/10
= 3x2/5x2 + 1/10 = 6/10 + 1/10 = 7/10
3/7 - 2/21 = 3x3/7x3 - 2/21 = 9/21 - 2/21 = 7/21
1/10 + 1/2 + 3/5 = 1/10 + 1x5/2x5 + 3x2/5x2 = 1/10 + 5/10 + 6/10 tu finis
et 1/22 - 1/11 = 1/22 - 1x2/11x2 tu finis
