8*10³ standard notation

Steve is scuba diving near his home in maui. at one point he is 100 feet below the surface. represent this number with a negative number. if he descends another 5 feet, what negative number will represents his.

If jm equals 5x -8 and lm equals 2x -6 which expression represents jl

Eden has a part time job. she is paid ? 7.20 an hour the week she worked 18 and a half hours how much is she paid