@Chris, but:
# set dist from input "Enter miles traveled: "
# make sure dist is a number, and if not print error and restart
# if dist is 0.0, print error and restart
# set guse from input "Enter gas used in gallons: "
# make sure guse is a number, and if not print error and restart
# set mpg to dist divided by guse
# if guse is 0.0, print error and restart