a] 10x-8.2*3=0.4
10x=0.4+24.6=25
x=2.5
b](1/2-2/7)÷9/28=(7/14-4/14)*28/9=(3/14)*(28/9)=2/3
c](1/4+7/4)*1/2-1/5=8/4*(1/2)-1/5=1-1/5=4/5=0.8
a] 10x-8.2*3=0.4
10x=0.4+24.6=25
x=2.5
b](1/2-2/7)÷9/28=(7/14-4/14)*28/9=(3/14)*(28/9)=2/3
c](1/4+7/4)*1/2-1/5=8/4*(1/2)-1/5=1-1/5=4/5=0.8