You and your friend have gift cards to a shopping mall. Your card has a value of 50$ and your friends card has a value of 30$. If either of you uses the cards, the value begins to decrease at a rate of $2.50 per month after 6 months.
a.Write two equations, one that gives the value of your card and another that gives the value of your friends card as functions of the number of months after 6 months of nonuse.
b.How are graphs of these functions related? How do you know.
c.What are the x intercepts of the graphs of the functions, and what do they mean in this situation.

Question

anonymous · Answer

such that x = 1 means 6months ?

x-time

a. yours equation : 
50 -2.5x

your friend :
30 - 2.5x
b. the graphs are parallel .. same slope (-2.5)
c. x intercept means when your gift card reached value of 0 which means you cant use it anymore ..

50 -2.5x = 0
2.5x=50
50/2.5 = x
x = 20

so 20 months after the 6 means your card will expire .. (26 total)
do the same with the other equation