a) \(7,3\times x+2,3\times x=25,6\times9,6\)
\(\Rightarrow(7,3+2,3)\times x=245,76\)
\(\Rightarrow9,6\times x=245,76\)
=> x = 25,6
b) x : 4,75 = 31,24 - 25,64
=> x : 4,75 = 5,6
=> x = 26,6
c) \(\frac{3}{4}\times x+\frac{1}{2}\times x-15=35 \)
=> \((\frac{3}{4}+\frac{1}{2})\times x=50\)
=> \(\frac{5}{4}\times x=50\)
=> \(x=40\)
d) \(27,5\times\frac{8.4}{x}\times7=21\)
=> \(\frac{8.4}{x}\times7=\frac{42}{55}\)
=> \(\frac{8.4}{x}=\frac{6}{55}\)
=> x = 77