(3,4+7) х (-1 7/18) = -14 4/9
1) 3,4 + 7 = 10,4
2) 10,4 х (-1 7/18) = 10,4 х (-25/18) = -130/9 = -14 4/9
Б)456+12b=840
12b=840-456
12b=384/:12
b=32
a)14p-420=630
14p=630+420
14p=1050/:14
p=75
S=Пr^2
r=d/2=6.2÷2=3.1см
S=3.14×3.1^2=3.14×9.61=30.1754==30,2см.кв.