Find the domain of f(x) = x+5/ 2-x

Since the value decreases by 25% each time, the next cost is the current cost times 0.75 (since new cost is 75% of current cost).to find the value of the book after x times sold, you can use:   just plug in the number of times it is resold to find the value.or you can do it this way a exponential function would represent it nicely f(x)=b*a^xreason being a decrease of %a = 1+rr = -25% = -0.25and b being what the original cost of the bookf(x)=85*0.75^xwhere f(x) is the price after x amount of previous owners