SOLUTION: Hi A clothing shop paid $1,620 for suits to be sold at a profit of $15 each. When he had sold all but 9 suits, he had recovered the cost. Assuming that each suit cost the same,h

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: Hi A clothing shop paid $1,620 for suits to be sold at a profit of $15 each. When he had sold all but 9 suits, he had recovered the cost. Assuming that each suit cost the same,h      Log On

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Question 1163060: Hi
A clothing shop paid $1,620 for suits to be sold at a profit of $15 each. When he had sold all but 9 suits, he had recovered the cost. Assuming that each suit cost the same,how many did he buy and how much did he pay for each one.
Thanks

Found 3 solutions by Theo, MathTherapy, greenestamps:
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
let c be the cost of each suit.
let s be the selling price of each suit.
then xc = total cost and xs = total selling price.
you are given that 1620 is the total cost.
this means that xc = 1620
you are given that the total cost is achieved when all but 9 suits are sold.
this means that xc = (x - 9) * s.
since xc = 1620, you get:
1620 = (x - 9) * s
you are given that the profit on each suit is 15.
this means s = c + 15
therefore:
1620 = (x - 9) * (c + 15)
simplify this to get:
1620 = xc + 15x - 9c - 15*9
simplify further to get:
1620 = xc + 15x - 9c - 135
since xc = 1620, this becomes:
1620 = 1620 + 15x - 9c - 135
subtract 1620 from both sides of this equation to get:
0 = 15x - 9c - 135
add 35 to both sides of this euation to get:
135 = 15x - 9c
since xc = 1620, then c must be equal to 1620 / x
replace c with 1620/x to get:
135 = 15x - 9*1620/x
multiply both sides of this equation by x to get:
135x = 15x^2 - 14580
subtract 135x from both sides of the equation to get:
0 = 15x^2 - 135x - 14580
divide both sides of this equation by 15 to get:
0 = x^2 - 9x - 972
factor this equation to get:
(x + 27) * (x - 36) = 0
solve for x to get:
x = 36 or x = -27
x has to be positive, so x = 36.
go back to your original equations to get:
xc = 36*x = 1620
solve for c to get c = 45.
since s = c + 15, then s = 60.
your total cost is when all but 9 suits are sold.
this means that (x-9) * 60 = 1620
since x = 36, this becomes 27 * 60 = 1620 which becomes 1620 = 1620.
this confirms that x = 36 is correct.
the cost for each suit is 1620/36 = 45.
that's your solution.

Answer by MathTherapy(10556) About Me  (Show Source):
You can put this solution on YOUR website!
Hi
A clothing shop paid $1,620 for suits to be sold at a profit of $15 each. When he had sold all but 9 suits, he had recovered the cost. Assuming that each suit cost the same,how many did he buy and how much did he pay for each one.
Thanks
ONLY 1 variable is necessary here. The more variables used, the more complex this problem becomes, in MOST cases.


Let number he bought be S    
Then amount he paid for each suit was: %221%2C620%22%2FS
Amount sold to break-even: S  -  9
Since profit on each was $15, then price he sold EACH of the S - 9 for, was %221%2C620%22%2FS+%2B+15
We then get the following BREAK-EVEN equation: 
 ---- FOILing the left-side of equation

matrix%281%2C3%2C+15S++-++%2214%2C580%22%2FS++-++135%2C+%22=%22%2C+0%29
matrix%281%2C3%2C+15S%5E2++-++135S+-+%2214%2C580%22%2C+%22=%22%2C+0%29 ------ Multiplying by LCD, S
matrix%281%2C3%2C+15%28S%5E2+-+9S+-+972%29%2C+%22=%22%2C+15%280%29%29 ---- Factoring out GCF, 5
matrix%281%2C3%2C+S%5E2++-++9S++-++972%2C+%22=%22%2C+0%29
(S  -  36)(S + 27) = 0
S - 36 = 0			                OR	   S + 27 = 0
Number of suits he bought, or highlight_green%28matrix%281%2C3%2C+S%2C+%22=%22%2C+highlight%2836%29%29%29   	OR         S = - 27 (ignore) 

Cost of each suit: 

You're right, GREENESTAMPS! Thank you. I made the correction. BTW, your answers are correct, and I've adjusted mine to match yours!
Thanks again!

Answer by greenestamps(13209) About Me  (Show Source):
You can put this solution on YOUR website!


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For tutor @MathTherapy....

(1) I firmly agree that the problem should be solved using a single variable.

(2) Check your solution where you factor out the LCM of 15....

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Let the number of suits be x.

The cost of each suit is 1620%2Fx

The sale price of each suit is 1620%2Fx%2B15

When (x-9) suits have been sold, the total sales is equal to the original cost:

%28x-9%29%281620%2Fx%2B15%29+=+1620
%28x-9%29%28%281620%2B15x%29%2Fx%29+=+1620
%28x-9%29%281620%2B15x%29+=+1620x
%28x-9%29%28108%2Bx%29+=+108x
x%5E2%2B99x-972+=+108x
x%5E2-9x-972+=+0
%28x-36%29%28x%2B27%29+=+0
x+=+36 (ignore the negative solution)

ANSWERS:

He bought x=36 suits

The amount he paid for each one was $1620/x = $1620/36 = $45

CHECK: (x-9) suits, sold at 1620/x+15 each, should equal 1620:

%28x-9%29%281620%2Fx%2B15%29+=+27%281620%2F36%2B15%29+=+27%2845%2B15%29+=+27%2860%29+=+1620