Evaluate f(-4) for the function f(x) = 5 - X.

Ineed with number 17 i don’t get it at alll

Amerchant has coffee worth $60 a pound that she wishes to mix with 50 pounds of coffee worth $90 a pound to get a mixture that she will sell for $70 a pound. how many pounds of the & 60 coffee should be used?

The price of an item has been reduced by 30%. the original price was $30. what is the price of the item now ?