720:(ax2+ax30)=2x6
(=)720:[ax(2+30)]=12
(=)720:(ax32)=12
(=)ax32=720:12
(=)ax32=60
(=)a=60:32
(=)a=15/8
720:(A.2+A.30)= 2.6
=> 720:(A.2+A.30)=12
=> A.2+A.30=720:12
=> A.2+A.30=60
=> A.(2+30)=60
=> A.32=60
=> A=60:32
=> A=\(\frac{15}{8}\)
Giải
Theo đề bài , ta có :\(720\div\left(a\times2+a\times30\right)=2\times6\)
\(\Leftrightarrow\frac{720}{a\times2+a\times30}=12\)
\(\Leftrightarrow\frac{720}{a\times2+a\times30}=\frac{12}{1}\)
\(\Leftrightarrow720\times1=12\left(a\times2+a\times30\right)\)
\(\Leftrightarrow720=12\left[a\left(2+30\right)\right]\)
\(\Leftrightarrow720=12\left[a\times32\right]\)
\(\Leftrightarrow a\times32=720\div12\)
\(\Leftrightarrow32a=60\)
\(\Leftrightarrow a=\frac{60}{32}\)
\(\Leftrightarrow a=\frac{15}{8}\)
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