[tex]a) \\ \\ ( \frac{1}{4} + \frac{5}{4} + \frac{6}{4} + \frac{23}{4}) - ( \frac{17}{4} + \frac{17}{4} - \frac{20}{4} + \frac{11}{4}) = \frac{1}{4} + \frac{5}{4} + \frac{3}{2} + \frac{23}{4} - ( \frac{17}{4} + \frac{17}{4} - 5 + \frac{11}{4}) = \frac{1}{4} + \frac{5}{4} + \frac{3}{2} + \frac{23}{4} - \frac{25}{4} = \frac{10}{4} = \frac{5}{2} \\ \\ b) \\ \\ a + \frac{6}{9} = \frac{20}{9} \\ \\ a + \frac{2}{3} = \frac{20}{9} \\ \\ a = \frac{20}{9} - \frac{2}{3} = \frac{14}{9} \\ \\ b - \frac{26}{3} = \frac{14}{3} \\ \\ b = \frac{14}{3} + \frac{26}{3} = \frac{40}{3} \\ \\ \frac{80}{10} - c = \frac{26}{10} \\ \\ 8 - c = \frac{26}{10} \\ \\ 8 - c = \frac{13}{5} \\ \\ - c = \frac{13}{5} - 8 = - \frac{27}{5} \\ \\ c = \frac{27}{5} \\ \\ \frac{30}{5} + d = \frac{98}{5} \\ \\ 6 + d = \frac{98}{5} \\ \\ d = \frac{98}{5} - 6 = \frac{68}{5} [/tex]
c)
50%•10000=0,5•10000=5000
75%•4500=0,75•4500=3375
