If 30 lb of rice and 30 lb of potatoes cost $31.80, and 20 lb of rice and 12 lb of potatoes cost $17.52, how much will 10 lb of rice and 50 lb of potatoescost?

Let x be the cost of 1 lb of rice and y be the cost of 1 lb of potatoes. Set up two linear equations from the given information using x and y as the variables.