5x + 3(10-x) + x = 45
5x + 3.10 - 3.x + x = 45
5x - 3x + x + 30 = 45
3x = 45-30
3x = 15
x = 15:3
x = 5
Vậy x = 5
\(5x+3\left(10-x\right)+x=45\)
\(\Leftrightarrow5x+30-3x+x-45=0\)
\(\Leftrightarrow3x-15=0\)
\(\Leftrightarrow3\left(x-5\right)=0\)
\(\Leftrightarrow x-5=0\)
\(\Leftrightarrow x=5\)
\(5x+3.\left(10-x\right)+x=45\)
\(\Rightarrow5x+30-3x+x=45\)
\(\Rightarrow3x+30=45\)
\(\Rightarrow3x=15\)
Vậy X=5
\(\Rightarrow x=5\)
5x + 3(10-x) + x = 45
5x + 3.10 - 3.x + x = 45
5x - 3x + x + 30 = 45
3x = 45-30
3x = 15
x = 15:3
x = 5
Vậy x = 5