Your parents have decided to buy a new toyota 4runner for 25,635. according to the dealer, the car will depreciate in value approximately $3,000 per year. write and solve a linear equation to find how many years it will be until the car is worth $3,135

Let the value of the car be represented by V and the amount of years by y. 
This gives us the following formula:
V = 25,635 - 3000y
(This is because we start with a value of $25,635 and the value decreases by $3,000 every year 'y')

Now, we want to know when the car is worth $3,135, so we know V = 3,135
Now we can make up our equation:
25,365 - 3,000y = 3,135

Collecting terms gives us:
-3,000y = -22,500

Finally we divide by -3,000 to find 'y'
y = -22,500 / -3,000 = 7.5

Hence, the car will be worth $3,135 after 7.5 years.

If i think this is what your asking, he should look at the grams or pounds/ounces and compare the to their cost then max can identify which one is proportional and which is not ( i think xd)

15 cm is the answer to your question