8х+21-6х=4х+3
8х-6х-4х=3-21
-2х=-18
х=9
23-12х-32+17х=1
5х=1-23+32
5х=10
х=2
22/21 - 29/42 = 44/42 - 29/42 = 15/42 = 5/14