This problem involves solving a system of algebraic equations from a context: depending how the problem is interpreted, there may be one equation or two.

This task provides an exploration of a quadratic equation by descriptive, numerical, graphical, and algebraic techniques. Based on its real-world applicability, teachers could use the task as a way to introduce and motivate algebraic techniques like completing the square, en route to a derivation of the quadratic formula.

This is an entire unit of activities relating to whole numbers, place value and rounding.  The activity I use is called "Reality Checking" on pages 57-64.  "Reality Checking" provides a real world connection for students to practice and apply the standard algorithm for addition and subtraction.  Students will work either individually, with a partner or group to balance a mock checking account.  Students will add whole number deposits and subtract whole number withdrawals while using estimation to check for reasonableness.

A list of sites that offer engineering ideas for teacher and student use. Offers a variety of lessons, units and/or activities at all levels.