2/5 + x = 15/20
2/5 + x = 3/4
x = 3/4 - 2/5
x = 7/20
8/9 - 2/9 : x = 2/3
2/9 : x = 8/9 - 2/3
2/9 : x = 2/9
x = 2/9 : 2/9
x = 1
\(\frac{2}{5}+x=\frac{15}{20}\)
\(\frac{2}{5}+x=\frac{3}{4}\)
\(x=\frac{3}{4}-\frac{2}{5}\)
\(x=\frac{7}{20}\)
\(\frac{8}{9}-\frac{2}{9}:x=\frac{2}{3}\)
\(\frac{2}{9}:x=\frac{8}{9}-\frac{2}{3}\)
\(\frac{2}{9}:x=\frac{2}{9}\)
\(x=\frac{2}{9}:\frac{2}{9}\)
\(x=1\)
Mik làm chi tiết nhé, bạn có thể lược 1 số phần nếu thích
\(\frac{2}{5}+x=\frac{15}{20}\)
=>\(\frac{2}{5}+x=\frac{3}{5}\)
=>\(x=\frac{3}{5}-\frac{2}{5}\)
=> \(x=\frac{1}{5}\)
\(\frac{8}{9}-\frac{2}{9}:x=\frac{2}{3}\)
=> \(\frac{8}{9}-\frac{2}{9}:x=\frac{6}{9}\)
=> \(\frac{2}{9}:x=\frac{8}{9}-\frac{6}{9}\)
=>\(\frac{2}{9}:x=\frac{2}{9}\)
=> \(x=\frac{2}{9}:\frac{2}{9}\)
=> \(x=1\)