Solve only a) using excel

Two design alternatives (X and Y) are being considered for a new ride at the Disney Theme park. Alternative X requires a $400,000 investment and will produce net annual revenue of $43708 every year. Alternative Y requires a $ 480,000 investment and produces 1st year revenue of $ 43708; thereafter revenue decreases by $3,000 every year.

a)Based on a 6% MARR, which design alternative (X or Y) has the smallest Discounted Payback Period?