I am studying the linear programming and stuck with the following two problems. I don't have any clues how to convert programs with absolute terms into a linear program. I highly appreciate your help.
$min f(x)= 5 \lvert x-3\rvert + 2 \lvert x-5\rvert +3 \lvert x-9\rvert$
$min f(x)= \lvert x-y-7\rvert + \lvert 2x+3y-5\rvert + \lvert 3x+7+1\rvert$