I recently purchased a secondhand 2008 Toyota Camry. This car comes with a foot-operated parking brake instead of a hand brake. On a slope, I am able to manage a car from going backwards using the typical hand brake and accelerator. How do I do so with a foot brake? I have been taught to use only one foot for the brake and accelerator.
With an automatic transmission, the engine is always coupled to the drive wheels as long as the lever is in one of the drive modes (whether forward, reverse or sport). Hence, the car will not roll on a slope when you release the brake. It may either creep uphill or stay stationary - unless the slope is very steep.
Even then, the transmission provides enough torque to delay a backslide. You should use your left foot on the brake pedal and release it as you apply acceleration with your right foot.
For cars with a robotised clutch or double-clutch gearboxes, the clutch is disengaged whenever the car is at a standstill (even if the gear selector is in Drive).
On a slope, the car could roll back. So you must hold the brake with your left foot and release only as you accelerate to move off. What you should never do with these transmissions is release the brake and let the transmission hold the car on the slope. This will cause the clutch to slip. If this happens regularly, it will lead to premature wear.
There is no rule that says you cannot use your left foot for the brake pedal.