Tavon has a gift card for $110 that loses $2.50 for each​ 30-day period it is not used. He has another gift card for $90 that loses $2 for each​ 30-day period it is not used. a. Write and solve an equation for the number of​ 30-day periods until the value of the gift cards will be equal.
b. What will the value of each card be when they have equal​ value?

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

  +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

answer: c, the green line

step-by-step explanation:

there is no black line, eliminate b.

simple interest implies periodic payments, but the red line shows no payments, eliminate d.

simple interest has equal payments. if paid say every day, the graph is about a straight line (actually a stairstep).

the yellow line is not straight, eliminate a.

check: the green line is straight, answer is c.

simple interest with positive interest rate gives a straight line sloping up to the right. green line:

g(t) = $100 + ($200-$100) ÷ (20 years) × (t years)

= $100 + (4%/year) × ($100)(t years)

incidentally, the yellow line curving upward represents continuously compounded interest

y = $100 × 2^(t years / (14 assuming the yellow line hits $200 at 14 years. 2^0 is 1, so y(0) = $100; 2^(14/14) is 2, so y(14) = $200.

y=sec x is the correct answer

~batmans wife dun dun