40(целых) 3/4 + (10(целых) 27/40 - х) = 45(целых) 3/40

40 3/4+(10 27/40-х)=45 3/40 40 30/40+10 27/40-х=45 3/40 50 57/40-45 3/40=х х=5 54/40 х=6 14/40 х=6 7/20