A )$$3/5 , 7/10 , 13/20$$$$kgV (5 ; 10 ; 20)=20$$$$3/5=3*4/(5*4)=12/20$$$$7/10=7*2/(10*2)=14/20$$$$13/20=13/20$$
B)$$5/6 , 5/8 , 7/12$$$$kgV(6 ; 8 ; 12) =24$$$$5/6= 5*4/(6*4)=20/24$$$$5/8=5*3/(8*3)=15/24$$$$7/12=7*2/(12*2)=14/24$$
C)$$1/2 , 3/4 , 3/14$$$$kgV(2 ; 4 ; 14) = 28$$$$1/2=1*14/(2*14)=14/28$$$$3/4=3*7/(4*7)=21/28$$$$3/14=3*2/(14*2)=6/28$$