\(\Leftrightarrow\dfrac{1}{4}:x=\dfrac{5}{2}-\dfrac{3}{4}=\dfrac{7}{4}\)
hay x=7
3/4 + 1/4 : x = 5/2
1/4 : x = 5/2 - 3/4
1/4 : x = 10/4 - 3/4
1/4 : x = 7/4
x = 7/4 : 1/4
x = 7/4 x 4/1
x = 7
1/4:x= 5/2-3/4
1/4:x= 7/4
x= 1/4:7/4
x= 1/7
( dấu / là dấu gạch phần )