Пошаговое объяснение:
2x/9=(7/3):(21/4)
2x/9=7/3*4/21
2x/9=4/9
x=4/9 : 2/9
x=4/9*9/2
x=4/2=2
2х = 9 * 2 1/3 / 5 1/4
2х = 9 * 7/3 / 21/4
2х = 63/3 * 4/21
2х = 3/3 * 4/1
2х = 12/3
2х = 4
х = 4 : 2
х = 2
