What is the surface area of the rectangular prism?

Help plz

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 sum of two numbers is 12 and their difference is 18 what are the two numbers

What is the 17th term in the arithmetic sequence in which a6 is 101 and a9 is 83