a) x=\(\dfrac{-1}{3}\)+\(\dfrac{5}{4}\)
x= \(\dfrac{-4}{12}\)+\(\dfrac{15}{12}\)
x= \(\dfrac{11}{12}\)
b) x= \(\dfrac{-3}{4}\)+\(\dfrac{1}{2}\)
x= \(\dfrac{-3}{4}\)+\(\dfrac{2}{4}\)
x= \(\dfrac{-1}{4}\)
c) 75:[2(7.5)]=x.5
\(\dfrac{15}{14}\) =x.5
x= \(\dfrac{15}{14}\):5
x=\(\dfrac{3}{14}\)
d) (2.x)+3=13
2.x= 10
x= 5 (x≠0, thõa mãn yêu cầu của bài)