1) 657,239 ≈ 657,2 ; 0,512 ≈0,5; 57,429 ≈ 57,4; 99,98 ≈ 100,0
2) 8,32 ≈ 8,320; 49,0562 ≈ 49,056 ; 748,0998 ≈ 748,100
a)12y-3y=612
9y=612/:9
y=68
b)15x+7=82
15x=82-7
15x=75/:15
x=5
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