# Applications of linear equations

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##### Examples
###### Lessons
1. Find the equation of a line parallel to 3x + 5y = 9 with the same y-int as 4x -5y = 12
1. Find the equation of a line perpendicular to 3x + 4y = 12 with the same x-int as 2x - 6y = 0
1. Lines A & B are perpendicular and have the same x-int. The equation of line A is x + 2y - 4 = 0. Determine the y-int of line B.
1. Alex bought 144 bagels for $80. His profit was$75 once he had sold 100 bagels. Find the equation that represents Alex's profit P as a function of the number sold, n?
1. A super computer still has the value of $80,000 after two years, and$50,000 after four years. Determine the purchase price of the super computers
1. A house was purchased for $500,000. The owner expects the house to double in value in the next 12 years. Find the appreciation equation. 1. The total cost of a car is the sum of the selling price, plus a sales tax of 5%, plus a$100 environmental fee.
i)
Express the total cost of the car as a linear function of the selling price.
ii)
What is the total cost of a car that sells for $56,000? iii) What is the selling price of a car whose total cost was$72,000?
###### Topic Notes
We always encounter situations that can be expressed in linear equations. Watch this lesson and learn how to solve linear equations word problems.