Math Problem Statement

Mary Beth starts with $200 in her bank account. Every week she withdraws $15 for miscellaneous expenses. For how many weeks could she withdraw the money if she maintains a balance of at least $35? Write an inequality to represent the situation. Use x to represent the number of weeks.

Solution

Let's define the situation step by step and translate it into an inequality.

Variables and constants:

  • Mary Beth starts with $200.
  • Each week, she withdraws $15.
  • She wants to maintain a balance of at least $35 in her account.
  • Let xx represent the number of weeks.

Step-by-step translation:

  1. Each week, Mary Beth’s balance decreases by $15, so after xx weeks, she will have withdrawn 15x15x dollars.
  2. Her remaining balance after xx weeks will be her starting balance minus the total withdrawn: 20015x200 - 15x
  3. She wants this balance to be at least $35, so the inequality is: 20015x35200 - 15x \geq 35

Solving the inequality:

  1. Subtract 200 from both sides: 15x35200-15x \geq 35 - 200 15x165-15x \geq -165
  2. Divide both sides by -15 (remember to reverse the inequality sign because we are dividing by a negative number): x16515x \leq \frac{-165}{-15} x11x \leq 11

Conclusion:

Mary Beth can withdraw money for up to 11 weeks while maintaining a balance of at least $35.

Would you like further details or have any questions about this?

Here are 5 related questions:

  1. How much money will Mary Beth have after 8 weeks of withdrawals?
  2. What happens if she increases her weekly withdrawal to $20? How many weeks can she maintain a balance of $35?
  3. If her starting balance was $300 instead of $200, how many weeks could she withdraw $15?
  4. What if she wanted to maintain a balance of $50 instead of $35?
  5. If she deposits $10 every 3 weeks, how will this affect the number of weeks she can withdraw?

Tip: In inequalities, remember to reverse the inequality sign when multiplying or dividing by a negative number.

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Math Problem Analysis

Mathematical Concepts

Algebra
Inequalities
Linear Equations

Formulas

200 - 15x >= 35
Solving inequalities: dividing by negative numbers reverses the inequality sign

Theorems

Properties of inequalities

Suitable Grade Level

Grades 7-9