2x+3y+z i dont now how to do it

If a is a nonzero real number then the reciprocal of a is

Asalsa recipe uses green pepper, onion, and tomato in the extended ratio 3: 5: 7. how many cups of tomato are needed to make 105 cups of salsa? a. 7 b. 21 c. 35 d. 49

Milk and ice cream are mixed together for a recipe. the total volume of the mixture is 1 cup. if the milk contains 2% fat, the cream contains 18% fat ,and the mixture contains 6% fat ,how much cream is in the mixture