Question 1135536
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Let x be the number of $1.50 tiles.

Then the number of the $4.00 tiles should be (1000-x).


The total cost will be  1.50*x + 4.00*(1000-x)  dollars.


She wants the average cost would be $2 per square foot:


    {{{(1.50*x + 4.00*(1000-x))/1000}}} = 2.


Solve this equation.


    1.50*x + 4.00*(1000-x) = 2*1000


    1.5x + 4000 - 4x = 2000

    -2.5x = 2000 - 4000

    -2.5x = -2000  ===============>  x = {{{(-2000)/(-2.5)}}} = 800.


<U>ANSWER</U>.  800 tiles per $1.500 and the rest 1000-800 = 200 tiles per $4.00.


<U>CHECK</U>.   {{{(1.50*800 + 4.00*200)/1000}}} = 2.00 dollars.   ! Correct !
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