Abank offers a cd that pays a simple interest rate of 8%. how much must you put in this cd now in order to have $ 13,760 to replace all the windows in your house in 9 years?

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?

Jonathan can type 20 documents in 40 minutes ,and susan can type it in 30 minutes and jack can type it in 24 minutes working together ,how much time will it is take them type the same document

How is this equation completed? i cannot find any examples in the book.