Tavon has a gift card for $165 that loses $4 for each 30-day period it is not used. He has another gift card for $145 that loses $3.50 for each 30-day period it is not used. Write an equation for the number of 30-day periods until the value of the gift cards will be equal. Let x represent the number of 30-day periods.

x=20

Step-by-step explanation:

Let  = a 30 day period

The first equation is 50 - 2x (because you start with $50 and subtract 2 for each 30 day period)

The second equation is 40-1.5x

Set them equal to each other:  50 - 2x = 40 - 1.5x

Solve for x:

50 - 2x = 40 - 1.5 x

    +2x         +2x

50 = 40 + 0.5 x

-40   -40

10 = 0.5 x

20 = x

So there will be 20 30-day periods until the cards will be equal in value.

Check:  After 20 periods, 50 - 2(20) = $10 left

40 - 1.5(20) = also $10 left

f(x) = - 2/3x + 5; f(5/2)

substitute 5/2 in for x:

f(5/2) = -2/3(5/2) + 5

simplify the right side:

f(5/2) = -5/3 + 5

f(5/2) = 10/3

answer:

f(5/2) = 10/3

i hope this you!

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step-by-step explanation:

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