Help please, with explanation

3rd option

Step-by-step explanation:

A porportional relationship can be described by

where x is the number of days, y is the amounts of food and k is the constant rate. (for this instance)

Looking at Classrom B, the amounts of food and cinstant rate isn't porpotional. Soxthat eliminates B and D.

For the 3rd option, the food amount is porportional as x increases. The unit rate here is 1,9 so the correct option is the 3rd option.

Step-by-step explanation:

The cost of computer = $ 800

It losed 1/4th of value every year.

The value of computer after 0 years = cost of computer = $ 800

The value after 1 year = 800 - ( ) = $600

The value after 2 years = 600 - ( ) = $450

The value after 3 years = 450 - ( ) = $337.5

The value after n years = computer cost at (n-1) year -