a) 96 - 3 * (x+1) = 42
3 * (x+1) = 54
x+1 = 18
x = 17
b) x + 2 * x + 7 * x = 90
10 * x = 90
x = 9
\(\cdot96-3\times\left(x+1\right)=42\)
\(3\times\left(x+1\right)=96-42=54\)
\(x+1=54\div3=18\)
\(x=18-1=17\)
\(\cdot x+2x+7x=90\)
\(\left(1+2+7\right)x=90\)
\(10x=90\)
\(x=90\div10=9\)
a)96 - 3* (x + 1 ) = 42
3* ( x + 1 ) = 96 -42
3* (x + 1 ) =54
x + 1 = 54 : 3
x + 1 = 18
x = 18 - 1
x = 17
b) x + 2* x + 7* x = 90
x . ( 2 + 7 + 1)=90
x . 10 = 90
x = 90 : 10
x = 9
a) Ta có: \(96-3.\left(x+1\right)=42\)
\(\Leftrightarrow-3.\left(x+1\right)=42-96\)
\(\Leftrightarrow-3.\left(x+1\right)=-54\)
\(\Leftrightarrow x+1=\frac{-54}{-3}\)
\(\Leftrightarrow x+1=18\)
\(\Leftrightarrow x=18-1\)
\(\Leftrightarrow x=17\left(TM\right)\)
Vậy \(x=17\)
b) Ta có: \(x+2x+7x=90\)
\(\Leftrightarrow10x=90\)
\(\Leftrightarrow x=9\left(TM\right)\)
Vậy \(x=9\)