Posted by **matt** on Wednesday, January 7, 2009 at 10:39pm.

The tread depth of the tires on your family's new car is 3/8 inch. you predict that, as a result of driving the car, the change in tire tread depth will be about -3/64 inch per year.

A. write a variable expression for the tire tread depth after y years of driving. Use your expression to make a table showing the tire tread depth after 1,2 an 3 years.

b. Tires should be replaced when the tread depth is 1/16 inch. extend your table from part (a) to find the approximate number of years the car can be driven before the tires need to be replaced.

- math -
**Nancy**, Wednesday, January 7, 2009 at 11:02pm
Y = 3/8- ((-3/64)x) this is the variable expression.

just make y= 1/16 to find the number of years.

plug 1,2,3 into x to find the amount of tread left after each year.

- math -
**Reiny**, Thursday, January 8, 2009 at 8:42am
Nancy, you have a double negative, your equation would have the tread depth increase.

it should have been

depth = 3/8 - (3/64)t where t is number of years.

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