solve the question and how they get 47.5 in this solution , thank you

-35 Consider four alternatives, each of which has an 8-year useful life: If the MARR is 8%, which alternative should be selected? Solve the problem by benefit-cost ratio analysis. B/Cratio=($47.5(P/F,8%,8)/($10+$2.5(P/A,8%=($47.5(0.5403)/($10+$2.5(5.206)=1.11 The C - D increment is desirable. Reject D. B- C Increment B/Cratio=($2.3(0.5403)/$20=0.66 Reject B. A- C Increment