Algebra 1 - Linear Systems Best Method

Question

Solve the problem below using the method that you feel is the most efficient.

#5 2x+y=9 y=5x+2

#6 Eric sells model cars from a booth at a local flea market. He purchases each model car from a distributor for $14 and the flea market charges him a booth fee of $30. Eric sells each model car for $20.

How many cars will Eric have to sell to break even?

Answer 1

2x+5x+2=9

7x+2=9

7x=7

x=1

then y = 5(1)+2=7

(1,7) is the solution

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x is the # of cars

expense: 14x+30

income: 20x

14x+30=20x

30 = 6x

x=5

5 cars to break even