How to write 863.141 in expanded form

Use set builder notation to represent the following set: { -3, -2, -1, 0}

If 30 lb of rice and 30 lb of potatoes cost ? $27.60? , and 20 lb of rice and 12 lb of potatoes cost ? $15.04? , how much will 10 lb of rice and 50 lb of potatoes? cost?

Which expression is equal to (f+g)(x)?