А) 6/10 (4х-18)-4/10 (5-7х) б) 5 целых 1/4 (12-t)-3 целых 3/4 (-t-24) (даю 50 балов)

А)=4х•6/10-18•6/10-5•4/10+7х•4/10=
(24х-108-20+28х)/10=(52х-130)/10=
5,2х-13
б)=21/4(12-t)-15/4(-t-24)=
12•21/4-t•21/4+t•15/4+24•15/4=
63-21t/4+15t/4+90=
153-6t/4=153-3t/2