I need to know why vibration happens slowing down from 65 to stop and steering wheel shakes
Most likely warping or uneven wear on the rotors. This can be fixed in all but extreme cases by having the rotors "turned" or resurfaced. If this doesn't fix it, then you will need new rotors.
Two options, resurface the brake rotors or replace the rotors. Resurfacing it might be cheaper, but if go for the junk yard or aftermarket parts, you might find replacing rotors cheaper.
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