Question

các bạn giúp mình giải câu này nhé

39+2(31-x)=71

Answer 1

\(39+2\left(31-x\right)=71\)

             \(2\left(31-x\right)=71-39\)

             \(2\left(31-x\right)=32\)

                     \(31-x=32\div2\)

                      \(31-x=16\)

                                  \(x=31-16\)

                                  \(x=15\)

Answer 2

\(39+2\left(31-x\right)=71\)

\(\Leftrightarrow39+62-2x=71\)

\(\Leftrightarrow101-2x=71\)

\(\Leftrightarrow-2x=101-71\)

\(\Leftrightarrow-2x=30\)

\(\Leftrightarrow x=\left(-30\right):2=-15\)

Answer 3

\(39+2\left(31-x\right)=71\)

\(39+62-2x=71\)

\(101-2x=71\)

\(2x=30\)

\(x=15\)

vậy \(x=15\)