I need the evaluate of the expression HELP PLSSS

If f(x) =3x-2 and g(x) =2x+1 fins (f+ g) (x)

Cody started biking to the park traveling 15 mph, after some time the bike got a flat so cody walked the rest of the way, traveling 4 mph. if the total trip to the park took 6 hours and it was 46 miles away, how long did cody travel at each speed? solve using rate times time= distance

What does independent variable and dependent variable mean in math?