11. Suppose you get a job selling T-shirts at a concert. You get $2

for each T-shirt you sell, but it costs you $5 to get into the concert.

Let x represent the number of T-shirts you sell, and express the

amount of money you will get out of this deal as a function of x.

How many T-shirts will you have to sell to come home with $25?

 

 

Let x = the number of T-shirts you sell. Since each T-shirt

brings in $2, you multiply the number of T-shirts by $2 to get the

money from the sale of the T-shirts. This gives us

 

2x

 

But out of these proceeds must come the $5 you had to spend to get

into the concert. So we subtract 5 fro the 2x and get

 

2x - 5

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If the amount of money you need is $25, we get

 

2x - 5 = 25

 

Add 5 to both sides

2x

-

5

=

25

+

5

+

5

2x

=

30

 

Divide both sides by 2

 

x = 30/2

 

x = 15.

 

You would need to sell 15 T-shirts to come home with $25.

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Check: If you sold 15 T-shirts you could get $30 from the sale of the

T-shirts, so that when you took off the $5 you needed to get into the

concert, you would b e left with $25.

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