Preheat oven to 400 degrees F. Cut four large rectangular pieces of foil. On each piece, layer 1/4 of red bell peppers and 1/4 of broccoli. Drizzle with olive oil and then place salmon on top of the vegetables. Top the salmon with a drizzle of olive oil, a sprinkle of salt and pepper, and 2-3 lemon slices. Seal the aluminum foil packets and bake for 20-25 minutes.