115 - 5x = 25
=> 5x = 90
=> x = 18
vậy_
2(x + 3) = 10
=> x + 3 = 5
=> x = 2
vậy_
\(a.115-5x=25\)
\(\Leftrightarrow5x=90\)
\(\Leftrightarrow x=18\)
\(b.2.\left(x+3\right)=10\)
\(\Leftrightarrow2x+2.3=10\)
\(\Leftrightarrow2x+6=10\)
\(\Leftrightarrow2x=4\)
\(\Leftrightarrow x=-2\)
a.115 - 5x = 25
5x = 90
x = 18
b. 2(x + 3 ) = 10
x + 3 = 5
x = 2
\(115-5x=25\)
\(115-25=5x\)
\(90=5x\)
\(=>18\)