tìm x biết
\(\frac{x}{3}\)-\(\frac{3}{4}\)=\(\frac{1}{12}\)
\(\frac{29}{30}\)- (\(\frac{13}{23}\)+x) =\(\frac{7}{69}\)
bài 2 tính
\(\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}+\frac{1}{110}\)
\(\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+.........+\frac{1}{49\cdot50}\)
GIÚP MK NHANH NHA THỨ 7 NỘP RỒI