4.8(5х-7у)-2/21*4,9х+5/18*4,5у-23 8/15х= -32,35у докажи тождества

24x-33,6y-7/15x+5/4y-23 8/15x=-32,35y
(24x-7/15x-23 8/15x)-(33,6y-5/4y)=-32,35y
(24x-24x)-(33 3/5y-1 1/4y)=-32,35y
0-(33 12/20y-1 5/20y)=-32,35y
-32 7/20y=-32,35y
-32,35y=-32,35y