Tính :
a, \(\frac{1}{5}+\frac{4}{10}+\frac{9}{15}+\frac{25}{25}+\frac{36}{30}+\frac{49}{36}+\frac{64}{40}\)\(+\frac{81}{45}\)
b, \(\frac{17,8\cdot3,7-7,8\cdot4,8+5,7\cdot17,8-4,6\cdot7,8}{11,2+12,3+13,4+12,6+11,5+10,4}\)
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thank you very much .
a,1/5+2/5+3/5+4/5+...+9/5
=(1+2+3+4+...+9)/5
=45/5
=9
b,17,8(3,7+5,7)-7,8(4,6+4,8)
=17,8.9,4-7,8.9,4
=9,4(17,8-7,8)
=9,4.10
=94