Tìm x, biết: a) \(\Large\dfrac{x}{7}=\dfrac{54}{42}\) b) \(\Large\dfra

Tìm x, biết:

a) \(\Large\dfrac{x}{7}=\dfrac{54}{42}\)

b) \(\Large\dfrac{25}{40}=\dfrac{5}{x}\)

Trả lời:

 

• A. a) x = 9
• B. b) x = 8

a) \(\Large\dfrac{x}{7}=\dfrac{54}{42} =>\dfrac{6x}{42}=\dfrac{54}{42} => 6x = 54 => x = 9\)

b) \(\Large\dfrac{25}{40}=\dfrac{5}{x}=>​​​​\dfrac{25}{40}=\dfrac{25}{5x}=>5x=40=>x= 8\)