Задание 7: а) (2t − 3 4/15) · 1,3 = 13/25; б) 2,25 + 0,5(11 − 3x) = 4 3/8.

а) \(3\frac4{15}=\frac{49}{15}\), \(1.3=\frac{13}{10}\).

\[\left(2t-\frac{49}{15}\right)\cdot\frac{13}{10}=\frac{13}{25}\]

Делим на \(\frac{13}{10}\):

\[2t-\frac{49}{15}=\frac{13}{25}\cdot\frac{10}{13}=\frac25\]

\[2t=\frac25+\frac{49}{15}=\frac6{15}+\frac{49}{15}=\frac{55}{15}=\frac{11}{3}\]

\[t=\frac{11}{6}=1\frac56\]

б) \(4\frac38=\frac{35}{8}\), \(2.25=\frac94\), \(0.5=\frac12\).

\[\frac94+\frac12(11-3x)=\frac{35}{8}\]

\[\frac12(11-3x)=\frac{35}{8}-\frac{18}{8}=\frac{17}{8}\]

\[11-3x=\frac{17}{4}\]

\[-3x=\frac{17}{4}-11=\frac{17}{4}-\frac{44}{4}=-\frac{27}{4}\]

\[x=\frac{27}{12}=\frac94=2\frac14\]

Ответ: а) \(t=1\frac56\); б) \(x=2\frac14\).