5. Найдите значение выражения: 1) 0,6(4x-18) - 0,4 (5-7х) при х=2 4/13; 2) 5 1/4(12-1)-3 3/4(-1-24) при t = -0,4.

1) \(0,6(4x-18) - 0,4 (5-7х)\) при \(x=2\frac{4}{13} = \frac{30}{13}\). \(0,6(4 \cdot \frac{30}{13}-18) - 0,4 (5-7 \cdot \frac{30}{13}) = 0,6(\frac{120}{13}-\frac{234}{13}) - 0,4 (\frac{65}{13}-\frac{210}{13}) = 0,6(\frac{-114}{13}) - 0,4(\frac{-145}{13}) = \frac{-68,4}{13} + \frac{58}{13} = \frac{-10,4}{13} = -0,8\)

2) \(5\frac{1}{4}(12-t)-3\frac{3}{4}(-t-24)\) при \(t = -0,4 = -\frac{2}{5}\). \(5\frac{1}{4}(12-(-\frac{2}{5}))-3\frac{3}{4}(-(-\frac{2}{5})-24) = \frac{21}{4}(12+\frac{2}{5}) - \frac{15}{4}(\frac{2}{5}-24) = \frac{21}{4}(\frac{60}{5} + \frac{2}{5}) - \frac{15}{4}(\frac{2}{5} - \frac{120}{5}) = \frac{21}{4} \cdot \frac{62}{5} - \frac{15}{4} \cdot \frac{-118}{5} = \frac{1302}{20} + \frac{1770}{20} = \frac{3072}{20} = 153,6\)