Lời giải:
$y: \frac{1}{8}+y\times 92=20100$
$y\times 8+y\times 92=20100$
$y\times (8+92)=20100$
$y\times 100=20100$
$y=20100:100=201$
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$y: \frac{1}{25}+y\times 75=25000$
$y\times 25+y\times 75=25000$
$y\times (25+75)=25000$
$y\times 100=25000$
$y=25000:100=250$