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Ch. 1 - Equations and Inequalities
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
Chapter 2, Problem 35

Solve each problem. See Example 4. Cody sells some property for \$240,000. The money will be paid off in two ways: a short-term note at 2% interest and a long-term note at 2.5%. Find the amount of each note if the total annual interest paid is \$5500.
Table showing two notes with amounts x and 240,000 minus x, interest rates 2% and 2.5%, and corresponding interest calculations.

Verified step by step guidance
1
Define variables for the amounts of the two notes. Let \(x\) be the amount of the short-term note at 2% interest, and \(y\) be the amount of the long-term note at 2.5% interest.
Write an equation representing the total amount of the property sold: \(x + y = 240000\).
Write an equation representing the total annual interest paid. The interest from the short-term note is \$0.02x$ and from the long-term note is \$0.025y$. The total interest is \(5500\), so the equation is \(0.02x + 0.025y = 5500\).
Use the first equation to express one variable in terms of the other, for example, \(y = 240000 - x\).
Substitute this expression for \(y\) into the interest equation and solve for \(x\). Once \(x\) is found, substitute back to find \(y\).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Simple Interest Formula

Simple interest is calculated using the formula I = P × r × t, where I is the interest, P is the principal amount, r is the interest rate, and t is the time in years. Understanding this formula is essential to relate the interest earned from each note to its principal and rate.
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System of Linear Equations

A system of linear equations involves two or more equations with multiple variables. Solving such systems helps find unknown values—in this case, the amounts of the short-term and long-term notes—by using methods like substitution or elimination.
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Total Amount Constraint

The total amount of the property sold ($240,000) is split between two notes. This constraint forms one equation where the sum of the two note amounts equals the total sale price, providing a key relationship to solve the problem.
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