the absolut value signs mean that whatever is inside of them, you make it positive. so 4x-7 could equal 13 or -13 or both
so 4x-7=13
add 7 to both sides
4x=20
divide both sides by 4
x=5
this is one solution
4x-7=-13
add 7 to both sides
4x=-6
divide both sides by 4
x=-1.5
x=5 or -1.5