7,5b-5,2-7,6b-0.8b=7.5b-8.4b-5.2=-0.9b-5.2=-7
Если провести высоту BK, то <B=25°
<K=90°
<A=180-(90+25)=65°
16/21х - 3/7х = 2.48 - 1.18
(16-9)/21х = 1.3
1/3х = 1.3
1.3*3х = 1
х = 1/3.9
х = 10/39
18х+23х-х при х=37
(18+23-1)*х=4х
4*37=148
45-5*72:9=5
6*9*46-45=54
35+36*87-86=71
63:63*24+57=81