Esque quel qu un peut m aider svp merci

bonjour

a = 4/3 - 8/21 = 28/21 - 8/21 = 20/21

b = - 20/30 + 1/7 = - 140/210 + 30/210 = - 110/210 =  -11/ 21

c = 1/4 - 14/2 = 1/4 - 28/4 = - 27/4 

d = 1 - 2/3 x ( 10/15 - 12/15) = 1 - 2/3 x - 2/15 = 1 + 4/45 = 45/45 - 4/45 = 41/45

e = 4/7 - 1/3 : ( - 15/6 + 4/6) = 4/7 - 1/3 : - 11/6 = 4/7 - 1/3 x 7/4 = 4/7 - 7/28
   = 16/28 - 7/28 = 9/28 

f = (2/5 - 3/4) : ( (1/2 - 4/3) = ( 8/20 - 15/20) : ( 3/6 - 8/6)
  = - 7/20 : - 5 /6 = - 7/20 x - 6/5 = 42/100 = 21/50

g = (5/4 - 6/3) : ( 1 -4/7) = ( 15/12 - 24/12) : ( 7/7 - 4/7) = - 9/12 : 3/7 = - 9/12 x 7/4 = - 63/84
= -3/4

h = 27/5 x 1/8 = 27/40

i = ( 5/9 - 18/9) : ( - 2/3 - ( - 20/12 - 3/12) 
i = - 13/9 : ( - 2/3 + 17/12) = - 13/9 : ( ( - 8/12 + 17/12) = - 13/9 : 9/12
 = - 13/9  x 12/9  = -156/81 = - 52/3

j = ( 9/12 - 10/12) - ( 7/2 - ( 3/5 - 10/5) = - 1/12  - ( 7/2 + 7/5)
  = - 1/12 - ( 35/10 + 14/10) = - 1/12 - 49/10 = - 10/120 - 588/120 = - 598/120 = - 299/60

[tex]A= \frac{4}{3}- \frac{7}{8} * \frac{1}{3} = \frac{4}{3} - \frac{7}{24} = \frac{32}{8} - \frac{7}{24} = \frac{24}{25} [/tex]
[tex]B= \frac{-4}{5} * \frac{5}{6} + \frac{1}{7} = \frac{-20}{30} + \frac{1}{7} = \frac{-140}{210} + \frac{30}{210} = \frac{-110}{210} = \frac{-11}{21} [/tex]
[tex]C= \frac{1}{4} -2* \frac{7}{2} = \frac{1}{4} -\frac{14}{2} = \frac{1}{4} - \frac{28}{4} = \frac{-27}{4} [/tex]
[tex]D= 1- \frac{2}{3} *( \frac{2}{3} -\frac{4}{5})= \frac{1}{3} - \frac{2}{3} *( \frac{5}{15} - \frac{12}{15} )= \frac{1}{3} - \frac{2}{3}* \frac{-7}{15} = \frac{1}{3} - \frac{-14}{45} \\ D = \frac{15}{45} + \frac{14}{45} = \frac{29}{45} [/tex]
[tex]E= \frac{4}{7} - \frac{1}{3} / ( \frac{-5}{2} + \frac{4}{6} )= \frac{ \frac{5}{21} }{ \frac{-11}{6} }= \frac{5}{21} * \frac{6}{-11} = \frac{-30}{231} =- \frac{10}{77} [/tex]
... Tu as compris le principe, après sa va facilement.

13.
A= .. = 1,25
... Je suppose que tu as compris aussi ici