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A cellphone store has 120 cell phones in stock. Of these, 45 have keyboards. The manager of the store wants to add more cell phones with keyboards so that 40% of the stock has keyboards.

User VLeonovs
by
8.4k points

1 Answer

2 votes

Answer:

5

Explanation:

Let x be the number of cell phones with keyboards needed.

40% =
(40)/(100)


(x+45)/(x+120) =
(40)/(100)

x+45 = 40 -----1

x+120 = 100 -----2

You would want to make the total of 1 the same as 2.


(100)/(40): 2.5+112.5 = 100 -----3

Now 2 and 3 are equal.

x+120 = 2.5x+112.5

Isolate the x and numbers.

120-112.5 = 2.5x-x

Simplify.

1.5x = 7.5

x =
(1)/(1.5) × 7.5

x = 5

The manager of the store needs to add 5 more cell phones with keyboards.

User Dana Benson
by
7.7k points
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