1 gallon of white or any other vinegar. 4.55 litres, if you're into the new fangled stuff
I sue a large mug of normal salt.
A squirt of washing up liquid.
Shake it and then spray the weeds. I normally go for the base of the weed. Don't do it in full sun, it dries too quickly.
It's safe for pets - the sheep love it when I spray the hedge
Molly will eat the grass too