To write the inequality for the number of weeks Lily will need to save, we can start by considering her initial amount and her weekly earnings.
- Initial amount from her grandfather: $40
- Weekly earnings from tutoring: $65 per week
- Total amount needed to buy the cellphone: $300
After \( x \) weeks, the total amount of money Lily will have is given by the initial amount plus her earnings over those weeks:
\[ 40 + 65x \]
We want this amount to be at least $300, leading to the inequality:
\[ 40 + 65x \geq 300 \]
To find the number of weeks \( x \), we can solve the inequality:
- Subtract 40 from both sides:
\[ 65x \geq 300 - 40 \] \[ 65x \geq 260 \]
- Divide both sides by 65:
\[ x \geq \frac{260}{65} \] \[ x \geq 4 \]
Thus, the inequality is:
\[ 65x + 40 \geq 300 \]
Lily must save for at least 4 weeks to have at least $300.