Question 967196
T = number of years.


L(T) = 855 - 146 * T
D(t) = 697 - 80 * T


you want to know when L(T) will be less than D(T).


equation is L(T) < D(T) which becomes 855 - 146 * T < 697 - 80 * T.


subtract 697 from both sides of the equation and add 146 to both sides of the equation to get:


855 - 697 < 146 * T - 80 * T


combine like terms to get 158 < 66 * T


divide both sides of the equation by 66 to get 2.393939394 < T.


this is the same as T > 2.393939394.


the price of the laptop will be less than the price of the desktop in 2.393939394 years.


let's assume 2.4 years to test this out.


L(T) = 855 - 146 * T becomes 855 - 146 * 2.4 which is equal to 504.6.
D(t) = 697 - 80 * T becomes 697 - 80 * 2.4 which is equal to 505.


the laptop has become cheaper than the desktop when T is greater than 2.393939394 years.