280/46=6,086956522 (610/608)=1,003289474
1 способ
АВС+СВD=ABD
30+80=110градусов - АВD
2 способ
80-30=50градусов - АВD
<span>91 * 2/5 :5 3/5 + 3 48/100 : 6/25=21
1) 91*2/5=182/5
2) 182/5: 5 3/5=182/5:28/5=182*5/5*28=13/2
3) 3 48/100:6/25=348/100*25/6=29/2
4) 13/2+29/2=42/2=21</span>