Tavon has a gift card for $ 90 that loses $ 4 for each 30-day period it is not used. He has another gift card for $ 80 that loses $ 3.50 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?

it will take twenty 30-day periods until the value of the gift cards will be equal.

The value of each card be when they have equal value is $10

Step-by-step explanation:

Let x represent the number of 30-day periods until the value of the gift cards will be equal.

Tavon has a gift card for $90 that loses $4 for each 30-day period it is not used. This means that x 30-day periods, the amount left would be

90 - 4x

He has another gift card for $ 80 that loses $ 3.50 for each 30-day period it is not used. This means that x 30-day periods, the amount left would be

80 - 3.5x

For the amounts left in each card to be the same, the number of periods would be

90 - 4x = 80 - 3.5x

90 - 80 = - 3.5x + 4x

10 = 0.5x

x = 10/0.5

x = 20

The value of each card be when they have equal value is

90 - 4 × 20 = 90 - 80

= $10

step-by-step explanation: a reaction is first order. if the initial reactant concentration is 0.0200 m, and 25.0 days later the concentration is 6.25 x 10-4 m, then its half-life is:

4

step-by-step explanation:

im pretty sure it's 4 beacsue 8/2 equals 4