Keith applies a new brand of fertilizer to his grass.
He finds that the rate at which the grass grows can be modeled by a linear function.
He observes that the rate of growth is 1 centimeter every 3 days.
After 18 days, he measures the height of the grass to be 8 centimeters.
The initial height of the grass was c entimeters tall.

Sandy is upgrading her internet service. fast internet charges $20 for installation and $52.45 per month. quick internet has free installation but charges $57.45 per month. part 1 out of 2 complete the equation that can be used to find the number of months after which the internet service would cost the same. use the variable x to represent the number of months of internet service purchased.