Tìm x, biết: a) x:2,2 = (28,7-13,5).2

a) \[x:2,2 = \left( {28,7-13,5} \right).2\]

\[x:2,2 = 15,2.2\]

\[x:2,2 = 30,4\]

\[x = 30,4.2,2\]

\[x = 66,88\]

Vậy \[x = 66,88\].

b) \(1\frac{3}{4} - 2.\left( {\frac{1}{2} + x} \right) = \frac{3}{2}\)

\(2\left( {\frac{1}{2} + x} \right) = \frac{7}{4} - \frac{3}{2}\)

\(2\left( {\frac{1}{2} + x} \right) = \frac{1}{4}\)

\(\frac{1}{2} + x = \frac{1}{8}\)

\(x = \frac{1}{8} - \frac{1}{2}\)

\(x = \frac{{ - 3}}{8}\)

Vậy \(x = \frac{{ - 3}}{8}\).