выполните дефствия 3/4:5/6+2 1/2×2/5-1:1 1/6

-5,1................................................

3/5:5/6=3/5*6/5=18/25
1/2*2/5=1/5
1:1/6=1*6/1=6/1=6
18/25+1/5-1=22/25