6/11 * 4/7 = (6*4)/(11*7) = 24/77
7/20 * 10/21 = (7*10)/(20*21) = (1*1)/(2*3) = 1/6
8/9 * 27/32 = (8*27)/(9*32) = (1*3)/(1*4) = 3/4
23/28 * 49/46 = (23 * 49)/(28*46) = (1*7)/(4*2) = 7/8
34/86 * 43/51 = (34*43)/(86*51) = (34*1)/(2*51) = 17/51 = 1/3
7/18 * 90/77 = (7*90)/(18*77) = (1*10)/(2*11) = 5/11
63/64 * 48/91 = (63*48)/(64*91) =(7*9*6*8)/(8*8*7*13) =
=(9*3)/(4*13)= 27/52
36/85 * 34/39 = (36 *34)/(85*39) = (3*12* 2*17)/(5*17*3*13)=
= (12*2)/(5*13) = 24/65