a) 4/5x + 3/10(x-5)=7/10
4/5.x + 3/10.(x-5)=7/10
4/5.x + x-5 = 7/10:3/10
4/5.x + x-5=7/3
x + x - 5 = 7/3:4/5
x + x - 5 = 35/12
x.2 = 35/12 + 5
x.2 = 95/12
x = 95/12:2
x = 95/24
Vậy x = 95/24
Chưa chắc đúng :))
b) Ta có: \(\left(3\dfrac{2}{3}x-38\right)\cdot\dfrac{1}{70}=70\%\)
\(\Leftrightarrow x\cdot\dfrac{11}{3}-28=\dfrac{7}{10}:\dfrac{1}{70}=7\cdot7=49\)
\(\Leftrightarrow x\cdot\dfrac{11}{3}=77\)
hay x=21