578.
8 9/20*2/13=169/20 * 2/13=13/10=1 3/10
5 1/3 * 3/8=16/3 * 3/8=2
10 1/2 * 2/7=21/2 * 2/7=3
5/6 * 1 5/6=5/6*11/6=55/36=1 19/36
3 1/9 * 3/8=28/9 * 3/8=7/6
9 1/7 * 3/4=64/7 * 3/4=48/7=6 6/7
10 1/5 * 10/17=51/5 * 10/17=3*2=6
3/11 * 5 1/2=3/11 * 11/2=3/2=1 1/2
579.
1) .....=(3*2)/(5*2*2*3)=1/10
2) ....=(2*3*7)/(3*3*2*5*8)=7/(3*5*8)=7/120
3) .....=(5*3*19*7*5)/(19*5*5*3*3*7)=1/3
4) ....=(10*11*12*13)/(13*12*5*11*2*10)=1/10
580.
1) ....=5/12 * 4+7=(5*4)/(3*4) +7=5/3+7=1 2/3+7=8 2/3
2) ....=4/9 * 3/4+2/3=1/3+2/3=3/3=1
3) ....=2/5+5/4 * 8/5=2/5+2=2 2/5
4) ....=23/10 * 5/2+1/2=23/4+1/2=5 3/4+2/4=5 5/4=6 1/4