A) The B/C ratio of an investment of $1,000 which gives $500 at the end every year for 5 years is __________, if money is worth 10%. Answer is 1.9, but how?

and

B) An engineering department is considering purchase of an advanced computational fluid dynamics software system to enhance productivity. The initial cost of the software is $55,000 but is expected to result in efficiency savings of $25,000 the first year, with this amount decreasing by $5000 per year thereafter. The payback period for the software is equal to ? Answer is 2.67 years. but how?