Algebra Lesson 8 – The Equation Behind an Old Trick
by Elaine Ernst Schneider
ANSWER:
To understand why the puzzle works, you must solve it algebraically.
Let x = your house number.
Let y = your age.
Let A = answer
Using the numbered list of instructions, set up the problem as an algebraic equation. It would look like this:
A = 50(2x + 5) + y + 365 – 615
100
A = 100x + 250 + y +365 -615
100
A = 100x + y
100
A = x + y/100
Therefore,
x = the house number (You started with this number.)
y/100 = your age (When you divide by 100, you move the decimal point two places to the left.)
To return to lesson 8, click here
For more articles by this Author Click Here
For more articles on Algebra Grade 9 Click Here
