1 3/4:7/10+1/4
(27 9/10-17 4/5)*3/5
23/81*3 6/7
7/8:1 5/15*3 2/1
(9 1/5-3 17/25)*2 1/2

13/4*10/7 +1/4= 130/28 + 1/4= 130/28 + 7/28= 137/28= 4 25/28

(279/10 - 89/5) * 3/5 = (279/10 - 178/10)*3/5=101/10*3/5=303/50=6 3/50

23/81*27/7=23/27*9/7=23/9*3/7=69/63=1 6/63

7/8*15/20*5=105/160*5/1= 105/32= 3 9/32