Question

Bài 3. Tìm x, biết:

Answer 1

a) \(\dfrac{27-x}{15}=\dfrac{5}{3}\)

    \(27-x=\dfrac{\left(5\times15\right)}{3}\)

    \(27-x=\dfrac{75}{3}\)

    \(27-x=25\)

            \(x=27-25\)

            \(x=2\)

b) \(\dfrac{5+x}{7}=\dfrac{24}{21}\)

    \(\dfrac{5+x}{7}=\dfrac{8}{7}\)

    \(5+x=\dfrac{\left(8\times7\right)}{7}\)

    \(5+x=\dfrac{56}{7}\)

    \(5+x=8\)

          \(x=8-5\)

          \(x=3\)

Answer 2

\(\dfrac{27-x}{15}=\dfrac{5}{3}\)

\(\dfrac{27-x}{15}=\dfrac{25}{15}\)

\(x=\dfrac{27}{15}-\dfrac{25}{15}\)

\(x=2\)

b)\(\dfrac{5+x}{7}=\dfrac{24}{21}\)

\(\dfrac{5+x}{7}=\dfrac{8}{7}\)

\(x=\dfrac{8}{7}-\dfrac{5}{7}\)

\(x=3\)

đây

Answer 3

2

3

Answer 4

a) 27−x=(5×15)3

    

    5+x=(8×7)7