a ) \(\frac{2}{3}-x=\frac{5}{4}\)
\(\Rightarrow x=\frac{2}{3}-\frac{5}{4}=\frac{-7}{12}\)
Vậy x= \(\frac{-7}{12}\)
\(a,\frac{2}{3}-x=\frac{5}{4}\)
\(\Rightarrow x=\frac{2}{3}-\frac{5}{4}\)
\(\Rightarrow x=-\frac{7}{12}\)
\(b,\left[124-\left(20-4x\right)\right]:30+7=11\)
\(\Rightarrow\left[124-20+4x\right]:30=11-7\)
\(\Rightarrow\left[104+4x\right]:30=4\)
\(\Rightarrow104+4x=120\)
\(\Rightarrow4x=120-104=16\)
\(\Rightarrow x=16:4\)
\(\Rightarrow x=4\)
~Study well~
#ARMY_BLINK#
b. [ 124 - (20 - 4x)] : 30 + 7 =11
[ 124 - (20 - 4x)] : 30 =11 - 7
[ 124 - (20 - 4x)] : 30 = 4
124 - (20 - 4x) = 4 x 30
124 - (20 - 4x) = 120
20 - 4x = 124 - 120
20 - 4x = 4
4x = 20 - 4
4x = 16
x = 16:4
x = 4
câu a là số âm thì lên lớp 7 mới học mà kì dậy !!!