Nhớ quy tắc:
x : y = ...
=> y = x: ...
=> x = ... nhân y
Tương tự áp dụng với cách làm suy ra:
y = 2/ 15 : (8/5 - 2/5)
\(\dfrac{2}{15}:y=\dfrac{8}{5}-\dfrac{2}{5}\)
\(\dfrac{2}{15}:y=\dfrac{6}{5}\)
\(y=\dfrac{2}{15}:\dfrac{6}{5}\)
\(y=\dfrac{2}{15}\times\dfrac{5}{6}\)
\(y=\dfrac{1}{9}\)
\(\dfrac{2}{15}:y=\dfrac{8}{5}-\dfrac{2}{5}\)
\(\dfrac{2}{15}:y=\dfrac{6}{5}\)
\(y=\dfrac{2}{15}:\dfrac{6}{5}\)
\(y=\dfrac{90}{10}=9\)
nhầm làm lại
\(\dfrac{2}{15}:y=\dfrac{8}{5}-\dfrac{2}{5}\)
\(\dfrac{2}{15}:y=\dfrac{6}{5}\)
\(y=\dfrac{2}{15}:\dfrac{6}{5}\)
\(y=\dfrac{10}{90}=\dfrac{1}{9}\)
