Precalculus Video Playlist

System of Equations 3 Variables, Elimination, Substitution, Graphing, Inequalities & Word Problems

This video shows you how to solve systems of equations by various methods including word problems. This video contains tons of practice problems and examples to help you prepare for your next algebra test or exam.

Here is a list of topics included in this video:
1. Solving systems of equations by elimination with two variables
2. How to solve systems of linear equations by substitution
3. solving system of equation by graphing – finding the point of intersection
4. How to solve systems of inequalities by graphing and shading in the right region
5. Solving systems of equations with 3 variables by elimination
6. How To Solve System of Equations With 3 Variables Using Matrices – Elementary Row Operations – row echelon form

7. Nickels, Quarters, & Dimes – Word Problem
A jar contains 50 coins which consist of nickels, dimes, and quarters. There are five more dimes than nickels and the total value is $8.25. How many nickels, dimes, and quarters are in the jar?

8. School Play Theater – Tickets Word Problem
A school play sells adult tickets for $12 and student tickets for $7. Three times as many student tickets were sold compared to adult tickets. The school theater raised a total of $990. How many student and adult tickets were sold?

9. Perimeter, Rectangle, Length, Width – Word Problem
The perimeter of a rectangle is 44 feet and the length is 1 more than twice the width. What are the dimensions?

10. Investment, Interest, Savings Account Word Problem:
John placed a total of $18,000 in two separate savings account. The first account pays 7% interest and the second account pays 9% annual interest. In one year, he earned $1480 in interest. How much did he invest in each account?

11. Chemist – Acid Solution Mixture Volume Word Problem:
A chemist has 20% and 40% concentrated solutions of phosphoric acid. How much or what volume of each solution should be mixed to get 40L of a 27.5% acid solution?

12. Sum and Difference of Two Numbers Word Problem:
The sum of two numbers is 55 and the difference is 15. What are the two numbers?

13. Sum and Product of Two Numbers Algebra Word Problem
The sum of two numbers is 17 and the product is 60. Find the two numbers.

14. Age Related Algebra Word Problem
Sally is twice as old as Julia and Tim is five years older than Julia. The sum of their ages is 69. What are their ages?

15. Past, Present, Future, Age Algebra Word Problem:
3 years ago, Kim was twice as old as John. 4 years later she will be 8 years older than John. Find their present ages.

16. Upstream Downstream Boat River Distance Rate Time Word Problem:
It takes 5 hour for a boat to travel 80 miles downstream and 10 hours for it to travel the same distance upstream against the river current. Calculate the speed of the boat in still water and the speed of the river.

17. Airplane Tail Wind Distance Rate Time Word Problem:
It takes an airplane two hours to fly with the support of a tail wind of 30mph. It takes it three hours to travel the same distance during the return trip against the same tail wind. What is the speed of the plane?

18. Two Trains Traveling In Opposite Directions Word Problem:
Two trains are currently 600 miles apart traveling in opposite directions. The first train is traveling east at 80mph and the second train is traveling west at 40mph. How long will it take for the two trains to meet?