Bài 1:
a) $-6.(-\frac23).0,25 = -6.\frac{2}{3}.0,25 = -4.0,25 = -1$
b) $-\frac{15}4.(\frac{-7}{15}).(-2\frac25) = -\frac{15}{4}.\frac{7}{15}.-\frac{12}{5} = -\frac{7}{4}.\frac{12}{5} = -\frac{21}{5} = -4,2$
c) $(-2\frac15).(\frac{-9}{11}).(-1\frac1{14}).\frac25 = -\frac{11}{5}.\frac{9}{11}.-\frac{15}{14}.\frac{2}{5} = -\frac{9}{5}.\frac{15}{14}.\frac{2}{5} = -\frac{27}{14} = -1,93$
d) $(-5\frac12).(\frac{-1}2)-\frac23.(-\frac23) = -\frac{11}{2}.\frac{1}{2} + \frac{2}{3}.\frac{2}{3} = \frac{11}{4} + \frac{4}{9} = 2,75 + 0,44 = 3,19$
e) $(1\frac14).(\frac{-8}{15})-\frac35+\frac25.(-\frac34) = \frac{5}{4}.\frac{-8}{15} - \frac{3}{5} + \frac{2}{5}.\frac{-3}{4} = -\frac{8}{6} - \frac{3}{5} - \frac{3}{10} = -1,33 - 0,6 - 0,3 = -2,23$
f) $(-0,125).(-16).(-\frac89).(-0,25) = 0,125.16.\frac{8}{9}.0,25 = 2.\frac{8}{9}.0,25 = \frac{16}{9}.0,25 = 0,44$
g) $\frac58+2\frac14.1\frac23-\frac14.\frac56 = \frac{5}{8} + \frac{9}{4}.\frac{5}{3} - \frac{1}{4}.\frac{5}{6} = \frac{5}{8} + \frac{15}{4} - \frac{5}{24} = 0,625 + 3,75 - 0,208 = 4,167$
h) $(13\frac9{11}:\frac{38}{49}-5\frac2{11}:\frac{38}{49}):(\frac{49}{38}.\frac5{11}) = (\frac{146}{11}.\frac{49}{38} - \frac{57}{11}.\frac{49}{38}).\frac{38}{49}.\frac{11}{5} = (\frac{686}{38} - \frac{267}{38}).\frac{38}{49}.\frac{11}{5} = \frac{419}{38}.\frac{38}{49}.\frac{11}{5} = 60,5$
i) $\frac{-23}{30}.\frac{-13}{56}.\frac{70}{23}:\frac{125}{75} = \frac{23}{30}.\frac{13}{56}.\frac{23}{70}.\frac{75}{125} = \frac{23}{30}.\frac{13}{56}.\frac{23}{70}.\frac{3}{5} = 0,1$
j) $\frac{11}{30}+\frac{18}{35}.(\frac{35}{54}-\frac{49}{18}-\frac{28}{48}) = \frac{11}{30} + \frac{18}{35}.\frac{35}{54} - \frac{18}{35}.\frac{49}{18} - \frac{18}{35}.\frac{7}{12} = \frac{11}{30} + \frac{18}{54} - \frac{18}{2} - \frac{21}{20} = 0,37 - 9 - 1,05 = -9,68$
Bài 2:
a) $\frac{-1}{10}+\frac25x+\frac7{20}=\frac1{10}$ => $x = \frac{1}{2}$
b) $\frac13+\frac12:x=-\frac15$ => $x = -6$
c) $-\frac23:x+\frac58=-\frac7{12}$ => $x = -\frac{3}{2}$
d) $\frac12x+2\frac12=3\frac12x-\frac34$ => $x = 2$
e) $\frac23x-\frac25=\frac12x-\frac13$ => $x = \frac{3}{5}$
f) $\frac13x+\frac25(x+1)=0$ => $x = -\frac{3}{2}$