Tìm x a) x + 2/3 = 5/4

a) \(x + \frac{2}{3} = \frac{5}{4}\)

\(x = \frac{5}{4} - \frac{2}{3}\)

\(x = \frac{{15}}{{12}} - \frac{8}{{12}}\)

\(x = \frac{{15 - 8}}{{12}}\)

\(x = \frac{7}{{12}}\)

b) \(\left( {x + \frac{3}{{10}}} \right).\frac{1}{2} = \frac{{17}}{{12}}\)

\(x + \frac{3}{{10}} = \frac{{17}}{{12}}:\frac{1}{2}\)

\(x + \frac{3}{{10}} = \frac{{17}}{{12}}.\frac{2}{1}\)

\(x + \frac{3}{{10}} = \frac{{17}}{6}\)

\(x = \frac{{17}}{6} - \frac{3}{{10}}\)

\(x = \frac{{85}}{{30}} - \frac{9}{{30}}\)

\(x = \frac{{85 - 9}}{{30}}\)

\(x = \frac{{76}}{{30}}\)

\(x = \frac{{76:2}}{{30:2}} = \frac{{38}}{{15}}\)