А) -3.15+(-5.25)+4=-3,15-5,25+4=-8,4+4=-4,4
б)10+(-4.3)-9.7=10-4.3-9.7=5,7-9,7=-4
в)-24.8+60+(-35.2)=-24.8+60-35.2=35,2-35,2=0
г)-15+(3.4)+6.6=-<span>15+3.4+6.6=-11,6+6,6=-5</span>
26×(х+427)=15756
26x+26*427=15756
26x=15756-26*427
26x=4654
x=4654/26
x=179
(0.25+0.31)*3= 0.56*3=1.68