54/72=3/4
56/68=14/17
18/64=9/32
81/54= 1 целая 1/2
24/36=2/3
<span>(8.3-k)*4.7=5.64
8,3-k=5,64:4,7
8,3-k=1,2
k=8,3-1,2
k=7,1
(9.2-m)*3.2=16
9,2-m=16:3,2
9,2-m=5
m=9,2-5
m=4,2
(4.75-2 1/8):0.8=(4 3/4-2 1/8):4/5=2 5/8:4/5=21/8*5/4=105/32=3 9/32
или так
</span>(4.75-2 1/8):0.8=(4,75 -2,125):0,8=2,625:0,8=3,28125
5/12 : 55/72 = 5/12 * 72/55 = 1 * 6/11 = 6/11