Oblicz (skracaj, jeśli to możliwe): Dam naj Plissssss

Mogę pomóc w a i b ;) a) 1/7*5/2= 5/14 8/5*11/12= 2/5*11/3=22/15 4/7*9/10=36/70 b) 6/7*21/30= 3/5 5/8*14/15= 14/29

3/7 * 5/6 = 5/14 8/5 * 11/12 = 22/15 = 1 i 7/15 4/7 * 9/10 = 18/35 5/6 * 8/15 = 4/9 6/7 * 21/30 = 3/5 5/8 * 14/15 = 7/12 1 i 1/3 * 2 i 1/4 = 4/3 * 9/4 = 3 2 i 1/2 * 1 i 1/7 = 5/2 * 8/7= 20/7 = 2 i 6/7 2 i 4/7 * 1 i 5/9 = 18/7 * 14/9 = 4