Under her cell phone plan, Sarah pays a flat cost of $69 per month and $4 per gigabyte. She wants to keep her bill at $83.80 per month. Write and solve an equation which can be used to determine gg, the number of gigabytes of data Sarah can use while staying within her budget.

Answer 1

To determine the number of gigabytes \( g \) that Sarah can use while keeping her total bill at or below $83.80, we can set up the following equation based on her cell phone plan:

1. The flat cost per month is $69.
2. The cost per gigabyte is $4.

The total cost \( C \) can be expressed as:

\[ C = 69 + 4g \]

We want to keep this total cost at $83.80, so we set up the equation:

\[ 69 + 4g = 83.80 \]

Now, let's solve for \( g \):

1. Subtract 69 from both sides:

\[ 4g = 83.80 - 69 \] \[ 4g = 14.80 \]

2. Divide both sides by 4:

\[ g = \frac{14.80}{4} \] \[ g = 3.70 \]

Since Sarah can only use whole gigabytes of data, we will round down to the nearest whole number:

\[ g = 3 \]

Thus, Sarah can use 3 gigabytes of data while staying within her budget of $83.80.