QĐMS :
X x 40/1200 + X x 30/1200 = 35 x 300/4 x 300 = 10500/1200
= X x 40 + X x 30/1200 = 10500/1200
= X x 70/1200 = 10500/1200
= X = 10500 : 70
= X = 150
\(\frac{x}{30}+\frac{x}{40}=\frac{35}{4}\)
\(\frac{4x}{120}+\frac{3x}{120}=\frac{1050}{120}\)
\(\Rightarrow4x+3x=1050\)
\(\Rightarrow7x=1050\)
\(\Rightarrow x=1050:7\)
\(\Rightarrow x=150\)
=> \(\frac{4x}{120}+\frac{3x}{120}=\frac{1050}{120}\)
=> \(\frac{7x}{120}=\frac{1050}{120}\)
=> 7x=1050 => x= 150