Đáp án:
$\text{a) 2015+5.[300-(17-7²)]}$
$\text{b) 20.(x-16)=180}$
$\text{GIẢI}$
$\text{a) 2015+5.[300-(17-7²)]}$
$\text{= 2015 +5.[300-(-32)]}$
$\text{= 2015+5.(332)}$
$\text{=2015+ 1660}$
$\text{=3675}$
$\text{b) 20.(x-16)=180}$
$\text{⇒ x-16 =180÷20}$
$\text{⇒ x-16=9}$
$\text{⇒ x=25}$
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