\(\dfrac{x}{49}=\dfrac{-3}{7}\)
ta có \(x\cdot7=49\cdot-3\)
hay \(x.7=-147\)
hay\(x=-147:7\)\(\Rightarrow x=-21\)
b) \(x-\dfrac{2}{12}=\dfrac{2}{3}\)
\(x=\dfrac{2}{3}+\dfrac{2}{12}\)
\(x=\dfrac{5}{6}\)
c) \(x-\dfrac{1}{9}=15-3\)
\(x-\dfrac{1}{9}=12\)
\(x=12+\dfrac{1}{9}\)
\(x=\dfrac{109}{9}\)