А) 0,9- 0,5=0,4
б) -5 * 4- 7=-20-7=-27
в)9 * 9- 7,5=81 -7,5= 73, 5
г) √25+24= <span>√49=7</span>
Ответ:
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<span>14(2y-3)-5(y+4)=2(3y+5)+5y
28y-42-5y-20 = 6y+10+5y
28y-5y-5y-6y=42+20+10
12y=72
y= 72\12
y=6
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</span>
C из 30 по 2=30!/28!*2!=29*30/2=29*15=435