a)4800 : ( X x 16 ) = 25
X x 16 = 4800 : 25
X x 16 = 192
X = 192 : 16
X = 12
b)2009 : ( 71 : x ) = 2009
71 : x = 2009 : 2009
71 : x = 1
x = 71 : 1
x = 71
Hok tốt
\(a)\)\(4800\div\left(x\times16\right)=25\)
\(\Leftrightarrow\)\(\left(x\times16\right)=4800\div25\)
\(\Leftrightarrow\)\(x\times16=192\)
\(\Leftrightarrow\)\(x=192\div16\)
\(\Leftrightarrow\)\(x=12\)
\(b)\)\(2009\div\left(71\div x\right)=2009\)
\(\Leftrightarrow\)\(\left(71\div x\right)=2009\div2009\)
\(\Leftrightarrow\)\(71\div x=1\)
\(\Leftrightarrow\)\(x=71\div1\)
\(\Leftrightarrow\)\(x=71\)