№154
(7-5*(1 2/3)):0.8+0.2 =
(7-5*5/3)/(8/10)+1/5 =
(7-25/3)*5/4+1/5 =
((21-25)/3)*5/4+1/5 =
(-4/3)*5/4+1/5 =
-5/3+1/5 =
-25/15+3/15 =
-22/15 = -1 7/15
№156
(2 1/4)*(4/15+0.9)-(1/6)*2.25 =
(9/4)*(4/15+9/10)-(1/6)*(9/4) =
(9/4)*(4/15+9/10-1/6) =
(9/4)*(8/30+27/30-5/30) =
(9/4)*(30/30) =
9/4 = 2.25