Câu trả lời:
a. [(6x-72):2-84]=5628
(6x-72):2 =5628+84
(6x-72):2 =5712
6x-72 =5712:2
6x-72 =2856
6x =2856+72
6x = 2928
x =2928:6
x = 488
Vậy x=488
b.( \(\dfrac{9}{2}\)-2x):75%=1\(\dfrac{1}{3}\)
(\(\dfrac{9}{2}\)-2x):\(\dfrac{3}{4}\) =\(\dfrac{4}{3}\)
\(\dfrac{9}{2}\)-2x = \(\dfrac{4}{3}\)×\(\dfrac{3}{4}\)
\(\dfrac{9}{2}\)-2x =1
2x =\(\dfrac{9}{2}\)-1
2x =\(\dfrac{9}{2}\)-\(\dfrac{2}{2}\)
2x =\(\dfrac{7}{2}\)
x = \(\dfrac{7}{2}\):2
x =\(\dfrac{7}{2}×\dfrac{1}{2}\)
x =\(\dfrac{7}{4}\)
Vậy x=\(\dfrac{7}{4}\)