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а) 2х/3 = 4/9 , 2х=3*4/9, 2х=12/9, х= 12/9 :2, х=2/3
б) 3х/5 = 9/10 , 3х=5*9/10, 3х=45/10, х=45/10:3, х=15/10, х=1,5
в) 8/15 = 6х/9 , 6х= 8*9/15, 6х=72/15, х=72/15:6, х=12/15, х =0,8
г) 12/13 = 18х/39, 18х=12*39/13, 18х=36, х=36/18, х=2
