30-100%
x-10%
x=30*10/100=3руб скидка
30-3=27 руб стоит ложка
500-27*10=500-270=230 руб сдача
<span>cos74+cos62+cos50= (cos74+cos50)+cos62=2cos((74+50)/2)*cos((74-50)/2)+cos62=2cos</span>62*cos12+cos62=cos62(2cos12+1)=2*cos62(cos12+1/2)=2*cos62(cos12+cos60)=2*cos62*2*cos((60+12)/2)*cos((60-12)/2)=4*cos62*cos36*cos24
<span>15.3:1.5=2х:8.2
2х=15,3*8,2:1,5
2х=83,64
х=41,82</span>
<span>0,3^ (3х-1)<0.09
</span>0,3 ^(3х-1)<0.3^2
3x-1>2
x>1